People recommend putting up to the match in your 401k because it's pretax. When you retire (or get older-whatever), you want to have some money pretax, and some money post-tax (Roth), so that your tax liability isn't so large when you stop making money. Putting in the match gets you your free money from your company, and then you put the rest in a post-tax account. If you still have leftover money, put the rest in pre-tax and call it a day. But, that's neither here nor there if you don't have a liquid (fairly easily accessible) emergency fund.
So, get an emergency fund together if you don't have one. The amount you keep depends on your situation. Most people say job loss, furnace goes out, roof gets a huge hole in it, car dies etc... Calculate how much you think you need and start funneling away. You can't take out of your retirement, so make sure you have money in the bank for your emergencies. I'm still building my Efund while I contribute to my Roth and my 401k. Luckily, I'm almost done.
There are online retirement calculators, so use that to see whether you have enough for your age, etc..they all give different numbers, so use a couple and see what it says.
As far as choosing what funds to invest in, there are tons of books (search the forums for book recommendation or website recommendations), and it will help you figure out what your risk tolerance is, and where you should put your money based on that. That is also an individual decision.
I don't know anything about getting shares of a company so I can't help you there. Any other questions, just ask. I would check out these forums and search for stuff. There is a TON of information and it's easier to do your own research and then ask if you're confused about something.