You can boot w/o a sdcard, but some things won't work, like downloading attachments in browsers or installing many games.
Something isn't right tho. Are you sure you watched for errors when formatting data, system, cache, etc?
Are you sure your downloaded roms were complete? (not corrupt zips?) I usually open zip archives with WinZip or WinRar and test the archive with them.
RE: gApps hanging, possibly holding down the power button and letting it power off, then booting again, might have helped.
Did you flash kernel with either rom?