1. Capos are useful to guitarists who want to play open chords on higher frets - or to guitards who have trouble playing in keys like Bb, Eb etc. For bass players, capos will only limit their options. We are less in need of open strings, compared to guitar guys.
I hate capos, but three of the songs I play (I'm a guitard too

), Sundown, Gordon Lightfoot; My Sweet Lord, George Harrison (of course); Night Moves, Bob Seger; all capo. No idea why. Capos are said to be used for a singer's voice range. Meh.
2. As for down tuning, I assume you mean tuning down all the strings (so we're not talking about drop tuning one or more strings). Down tuning will hurt the connection between your inner ear and your instrument, unless you keep your bass tuned down all the time - but what if you play in two different bands? So I wouldn't. Drop tuning is a seperate case. If your band uses drop tuning, it might be better to go along, because in that case you will need the open strings.
3. Write everything you do in a computer music notation program. These programs offer all transposing options you might need.
Generally: no capo, no down tuning. Better to transcribe your music.
Yes, I meant all the strings down 1/2 or 1 step. So I would not do that. No argument from me! I don't
hate re-tuning, but for 1 song I think it's a pain.
Bad Company recorded Bad Company in Ebm. So to play it properly on acoustic guitar (it is really done on piano), you downtune the whole guitar 1/2 step. So for the bass line I would not downtune I would use another voicing of Ebm, higher on the bass fretboard?
Any links to any of the the computer programs you mentioned? Right now when I transpose (and I do some, sometimes just to see how a song sounds in another key) I have my sheet with all the scales and just go one for one, chord for chord.
When I (try to) create a bass line that I can't find or I find one that looks like it sucks, I use Malcolm's "Can't Go Wrong Formula" of R or R 3 or R 3 5 (or b3 for minor chords of course) and combinations there of.
And thank you all very much for the help for a 2 month nooborn bass player.
