rooker wuz up.
You ask for many things lol, but i can try to explain.
I am no java programmer, i just got into into it, but i am a C# for 2 years or so........... other people will reply to my poor help i give you perhaps in better ways.
basic stuff
2 servers will come in handy. 1 Game server, 1 DataBase .
First of all, The gamer will first login to his user account, his name will be searched in the database. If his name is not found, he will be denied and must register because the game is so awesome lol. If his name is found, he will go to the member page. The member page will have it login to some game search engine. Okay now i will prob get ya lost maybe, maybe not. But Gamer1 and Gamer2 wants to talk (this is in the game while they are playing it, i will explain the gamer part of connection after (sorry if i a sound like yoda or something)....MMMM..Explain I Will) ). Okay since the website is the client program, we don't have to worry about installation or a program or you may want one. Okay. Gamer1 will send a messaged which will go to the server which will filter it to the person he is talking to which is Gamer2. ( I am not going to go in depth it will be a page long). Now the game stuff works just the same except its a game lol (so much for explaining ). Security, well i know alot of great people that can have that locked down like fort nox but remeber this "when there is a will, there is a way". As i said, preetie basic *cough*useless* stuff what i wrote, someone else will write you up something good because they got more experiance.
If you want more explained, I can explain more if ya want.
how much will this all cost? ......... I am not even in college or barely out of highschool, so i don't know the doggie dog world of money.
I say you get some books out and learn because it is really awesome to know and to learn. On some spare time from work or hobbie its all good.
www.titansedge.com and the ADMIN can help you out , with all your needs.