Babba,
Yes and yes...actually it is better to have a complex when taking B vitamins. The reason being that you will get better absorption of the B12 and there are many benefits to your body from the other Bs too. Especially stress relief, relaxation, concentration, focus, recovery, immunity, etc. You can also help your body use these Bs more effectively by taking Spirulina. I have just recently found that out, but Spirulina has been in the some of the Soy and Whey shakes that I have used for years. Guess I was getting the benefit without really knowing it.
You can also find good sources of Bs in Kale and I think in Yams.
Like I said, I just started the injects not too long ago, but I had always had to take soooo much of the oral for my body to absorb a fraction of them. After years of that it just seemed like such a waste, so I turned to this. I have been using a few cubic centimeters every few days until I feel that I get my body's level up to a good amount. Probably 3 weeks, then I will just go once a week because it does stay in your system some and from what I understand, once you get the level up, then it stays up for long periods of time. For instance my grandfather took 1 shot a week for 4 weeks and now just has one shot a month. I may eventually be able to go to 2-4 weeks also, but I know my body needs more with all the stress I put on it with weight lifting and cardio, etc.
Hope I have helped,