1. I use a "rule of thumb" of around 8-12 turns MAX. If a decent "special terrain" is in sight at the beginning or turns up in the first few rounds I'll settle right away. Sometimes you get two settlers at the beginning, so you can explore in two directions at once or settle the first right away and explore with the second for a few rounds. The best "special terrain" is Whales, which gives 2 of food, trade and shields (in Despotism). Your primary goal should be to get city growth going as soon as possible, but not sacrifice for a bad starting point. Note that Barbs do not begin to pop up until the 16th turn, so you can take some risks with undefended cities early on.
2. Once you get used to the way cities develop in Civ2 you will begin to know what a city will probably turn out like even before it is founded. Cities with 4 tiles between them will not share any tiles; 3 tiles between will share outer radius tiles, which are usually only necessary when the city gets above size 10. The extreme is 1 tiles between them (sometimes called ICS - Infinite City Squeeze/Sprawl/Sleaze...), which would force you to keep cities below size 6 but then not require much in the way of infrastructure. The advantage of closeness is easier defense, quicker settling, more cities and less corruption, but you have less choice in terrain.
BTW, welcome to CFC!