starlanes are independent of stargates. stargates link two systems anywhere. once built, it will do nothing until you put the planet focus to stargate in or out. (rather than research for example) the the price for instantanious travel will be that your planet will regress. but you can always put it on a gas giant outpost and be fine that way.
if you didn't change it, you get up to 10 autosaves every time you start a new turn. you can undo stuff by loading that.
starlanes are independent of stargates. stargates link two systems anywhere. once built, it will do nothing until you put the planet focus to stargate in or out. (rather than research for example) the the price for instantanious travel will be that your planet will regress. but you can always put it on a gas giant outpost and be fine that way.