I agree, if you have to ask, then you should start by answering those questions by doing research yourself instead of asking others on a message board.
I can tell you that Google has a few thousand servers running their search engine. I can't remember the exact number.
As for Instant Messaging, there are a few open source ones out there like Jabba which are easy to install and customize - but plenty of people have done that already.
The competition in search engines are stiff - even big players have tried it and gone.
The same goes for webmail - to distinguish themselves people are offering large amounts of hard drive space.
If you want to just "play around", you can start your own search engine, webmail and IM within 2 hours. But if you want to be serious, we are talking 90% advertising and promotion - marketing is key, and you need money to advertise. Start small first - never over-invest in hardware you don't need - many companies have gone bankrupt by spending half a million bucks on hardware to realize they are not getting the visitors that require it. So start small, always have hardware that is just enough, and advertise heaps.
finally, someone who can actually, help me
Well i am quie serious about this and understand that money and dedication would have to be put in. My friend and I are looking for a good team to put together if by any chance anyone is interested?