rss or rss2 and how do you find what your feed is? i have 2 for one

one wp blog now,
the wp2 had a question mark and it seemed unreadable by google???

i don’t know how i got the simple oldschool /feed/
on the end of my feed and i guess that means rss 1

is there a way to combine?
is rss1 diff from rss2

i think wp automatically sets up the feed, right? but what if there is a problem?

thanks!
macmomma