Be more specific. How are you doing your extract? What tek are you following?
Yes you should filter. Do it before you base the first time.
Yes, you can get away with 1 base step, but you should thoroughly wash the freebase alks to remove excess NaOH if you choose to base once.
Personally, I'd reacidify and refilter after the first base step, then do my second base phase with na2co3 and give it a quick cold water wash.
"Laws alone can not secure freedom of expression; in order that every man present his views without penalty there must be a spirit of tolerance in the entire population." -Albert Einstein
I'm not a big fan of SWIM. I mean, I've never met the guy, but any time I hear about him, he's doing something sketchy.