if you mean support by fighting along side you at the same time, no. they are completely separate from your main. However, you can mail un-bound gear between characters if needed. Asside from that, there's no reason why you shouldn't play an alt or two, although, you'll be playing through all the same content you just finished with your VA.
Playing everything from the start wouldnŽd be the problem but how can i teach my engineers on my tactical account new skills from my new engineering account ?
Also _very_ important. The BOs cannot outrank the PC. Its tempting to pull together some officers and train em up real solid, max skills, etc but ultimately you'll find that you can't accept them.
LT--Max Ensign Officer
LTC--Max LT Officer
CMD--Max LTC Officer
So at Cap rank its possible to pass off officers to yourself to max the skills in that rank--except the liberated borg BO.
It makes perfect sense to roll a new character. You will play the game from an almost different perspective. You cannot train one character with the other, but your characters can support each other in other ways. I have one Science Character maxed out in Research. My other characters send her all of the data samples they find, she makes and sends them upgraded equipment in return. No only do I not have to worry about spending time leveling all of my characters in research, it makes sense from on RP standpoint as well.