1. It depends.
If you only use the RTP-package then it probably is, but i dont expect ANYONE (i am serious) to pay for a game which is based on others work except some modification and 99% work made by others, not you, but that is only if they find out. But yet still, they wont buy it because of the poor quality.
WARNING (EXTREMELY IMPORTANT AS HELL)!!!
If you are going to use resources such as sprites, graphics and further so on, made by others, perhaps scripts, graphical/pixelate-related or anything else made/created/produced et.c by others, then you HAVE to ask them for permission, thus it MUST be official positive answer if you want to use it. Cause if you dont, then you might get into some really serious problem. Some worth mentioning is: Lawproblem, Jail, Economic taxes rise and much much more to do with the law itself as you are violating the rule of Copyright, which is being taken serious in MANY countries. Also, you will also get alot of problem with some people (me for instance) as alot of people really hate when other people take credits for what they hav'nt done, and will take any actions nessecarily to make it hell for you. Justice is EXTREMELY important for me, and for ALOT others. Also, if you do get a positive permission to be able to use the resources, make sure to credit the resourcer and if there is any catches, make sure to follow/ancomplish them as a part of the deal. I had a few things left to say on my mind, but i've seem to have forgotten them.
Final Notice: Make sure to have positive permission to use everything you are using such as graphics, scripts and other stuff which is NOT made by you. Editing others work wont make the resource yours, you STILL have to ask for permission, unless it is 100% yours.. not 99% or what ever.
You must pass the copyright law justicefily and make sure to follow the law itself. Otherwise, not only will you have trouble with the law, but also haters.
2. The answer is the same as mine with some exceptions.
RPG Maker XP created by Enterbrain is especially designed and created for creating Rollplaying Games ONLY! It is NOT designed for Massive Multiplayer Rollplaying Games, AT ALL! Thus in some countries, most of them though, it is against the Copyright law to be using product for wrong purposes, unless the creators/producers/company of/behind the product lets the buyers/owners to. But in this case, Enterbrain have NOT included this right. In case you want to make an MMORPG by of RMXP, you MUST (Absolutely must!) ask Enterbrain for permission. And it wont be easy though. You can go black, but you will be risking alot as hell, also, you wont be successful as incase if you do, then Enterbrain will find out about it and since you are successful, it is worth sueing you as they will earn great profit out of you cause you will be in debt of probably million of dollars and your life is screwed. So basicly, you are just making it worse for yourself.
Another notice:
But i just want to tell you that it IS possible to make an MMORPG by RMXP but dont expect it to go smooth as Tibia or any other 2D MMORPGs or 3D incase you are going to make it 2D. RMXP is NOT 100% stable and there is ALWAYS some bug. When you fix one, another will come up and then another again and so on. In my opinion, i dont know you and what your capabilities are but you will NOT be able to create a smooth and/or successful MMORPG with RMXP. If you want to make an MMORPG, please use other programs. Trust me.. you will FAIL! (Repeat: FAIL!)!
RPG Maker XP (RPG Tsukuru XP) created by Enterbrain was NOT created/produced for the purpose of MMORPG (Massive Multiplayer Online Roll-Playing Games)-creation. It was created for the purpose to let other players create their own RPG games (Roll-Playing Games) - ONLY!
If you want to create an MMORPG, make sure to have a crew/staff. As it is most likely impossible to create a good one yourself. But a miserable one is perhaps possible but yet that takes ALOT of time and using resources by others, you have to ask for permission. Also, dont expect anyone to spend money such as premiums or any benefits on your game unless they have a reason to. Dont expect players to pay for your lousy epic-phailed game created by RMXP. If you really want to make an mmorpg, perhaps not the best but suitable and playable, THEN FOR THE SAKE OF GOD, dont use RPG Maker XP or any other products that are not capable of it/suitable or designed for it. As you will get into both technical problems in the game (massive of it) and economical, as well as law problems with the cops and the law itself. DONT USE RPG MAKER XP TO MAKE MMORPGS!
I dont think anyone would like to pay to play your lousy epic failed mmorpg game. I dont think they even want to pay their TIME to play it. Also, you will most likely lose your interrest of creating one. Its not that easy.
Many people have tried and wanted to make one, so why should YOU success among the many others.
If you really are desperate for an MMORPG, then make sure to use progrems and technologies that are designed and/or capable of it. And make sure to have a staff of at least one specialized in every category such as Graphic designer and further such. And it takes alot of time to create an MMORPG, and money and you will have to be spending alot.
You will NOT be able to make a game without risking alot, wasting alot of time AND money! You MUST have money.
Also, in case you want to earn money on it, you HAVE to have the suitable age, and in most countries it is at least of age 18 or 21, to be the VD / or / the leader of the company or the game itself, to be able to make money.
Also, as if it will be a work, you have to pay your staff for their work cause they have to pay rent, food and maybe some money for their freetime and hobbies.
I get the idea of you being like 13 years old =P
If you hav'nt gone of school yet, do that first and go study into gaming-industries. Life is not easy!
- As for you asking those questions.
Please make sure to study gaming-industries and such, as you must have to, to be able to make money and for your game/product to go smooth. Not being successful (as that requires luck too), but good, making it possible for you to survive and pay you and your staff the money at least of the minimum wage, which in the most countries is about apprx. 2000 dollers a month. It waries from country to country and the BMI the country holds.
I am right now studying for medicine and doctor.. and my best advice is to stay away from this industry as you wont earn much and chance of being successful is lower than having the opportunity to earn at least 25000 dollers a month.
In case of any further questions, please PM them.
If you cant w8 for my answers, you can add me on msn =P But i do not want to post it here. PM me incase you want it.
p.S I am NOT an adult, but i still know how most of it works (or atleast most of it). How ever, i'll wont answer questions which requires answers that i do NOT know. As economics and worldmarketing is an important subject at the end of 9th grade.
NOTE: I do NOT hold any resposibilities of any kind of situations revolving this, as i am right now just trying to help and answer the questions of my own knowledge, opinion and thoughts.