Jojy
First time out of the vault

I've played (and beaten) Fallout 2, and I loved every minute of it. Put a touch over 200 hours in it over a couple of playthroughs. I picked up Fallout a while back on sale, and really want to play it. However, there are things I'm not entirely sure about, and would like to figure out before starting a playthrough.
Firstly, I've heard there is a time limit to finish the main quest, and that the game will end if you don't hurry. How long do I get, and does it limit the amount of exploration I can do by much? Also, can the game be continued after the end of the main quest?
Secondly, any tips before heading into Fallout 1? Nothing gamey and difficulty breaking, like finding a suit of power armor and a plasma rifle within 5 minutes, but just helpful hints that might not carry over from Fallout 2?
Firstly, I've heard there is a time limit to finish the main quest, and that the game will end if you don't hurry. How long do I get, and does it limit the amount of exploration I can do by much? Also, can the game be continued after the end of the main quest?
Secondly, any tips before heading into Fallout 1? Nothing gamey and difficulty breaking, like finding a suit of power armor and a plasma rifle within 5 minutes, but just helpful hints that might not carry over from Fallout 2?