2- I wouldn't get to see the real colours before buying them
Yes, that always remains a problem, for me at least! You'll never really get a true idea of what a colour is truly like unless you have it in front of you. Websites will show the colour it is
supposed to be, but more often than not it is way off.
I had quite a lot of frustration a while back trying to find a replacement for a discontinued GW colour. It was just a certain shade of brown, but ALL the paints which were SUPPOSED to be an exact copy were way off... Ultimately I ended up with loads of different shades of brown, and still not the one I was looking for (I have since given up the quest, and have adapted to another colour!)
What sort of thing are you planning to paint? Some things will require a lot of bright colours, whereas others will use just various shades of browns, greys etc.
You might find yourself buying lots of colours you don't ever need, and if money is tight you might want to avoid that, which can be done with a bit of forethought and planning.
You are really spoilt for choice for places to get paints online. Just search for your chosen brand....
I use Games Workshop (Citadel) and Vallejo. Do a search for either and I'm sure you'll find no end of online suppliers. GW paints are in flip-top pots, whereas Vallejo are in dropper bottles, both of which have pros and cons (I'm still not sure which I prefer myself).