Features of inexpensive DVD Recorders vs expensive ones

I just got my first DVD recorder a LITEON (LVW-5115GHC+) for only $90.
After recording a RW DVD, you can only erase the whole disc - not
sections or chapters. Is this normal for all DVD recorders or can more
expensive ones erase sections or chapters like a VCR. It also has
timer recording like a VCR.

Also, what type of DVD should I buy? (+R or -R) or (+RW or -RW) for
rewritable?
Is there any difference in the + or -?

Is there a general site that describes the above issues?
Thanks, Rick

Rick