PLA and bed heating? I've read different things about PLA and heat-bed. Some say it is not needed, others recommend 60-70°C, but not for the first layers.

For larger objects I often have the problem that the object does not stick to the blue-painters-tape-covered aluminium print plate. Instead the print "curls" up on one or more corners. To reduce this effect, I'm using a brim between 5 and 10mm. Depending on the size of the object the brim works quite well. Will heating the bed also improve the print quality by reducing the amount of heat warping / curling?
I actually find it's not needed for PLA. I generally have it heated to 40&nbsp;&deg;C and use blue painters tape along with some hairspray (I prefer Tresemme as it smells gorgeous).

I've experimented with a glass bed, and Buildtak but I find blue painters tape is the key. I overlap the blue tape ends to the bed so it sticks, then spray the hairspray onto the tape. Also bed leveling is super important as are your print settings. What you want for the first layer is to have it essentially "pushing" into the bed. That way it gets good contact and wont curl up during the print, though it can be a challenge to get off later.

TL;DR for PLA you dont need a heated bed, its more about the surface and 1st layer height.