Singing - different voices

[Schu]

Hi, haven't posted here for a while...

For some background, I compose, play piano, organ and clarinet, and have sung lots, but sporadically, since I was about 3 when I sang christmas carols over the radio in german, in a very sweet voice that stayed amazingly well in tune for a 3 year old.

Recently (for the last year), I've begun singing bass in lots of choirs and have become unsporadic about it. I started off as a low as hell bass (can comfortable get to Db, and at the time, I could hardly go above middle C), but lately I've been able to get F's and F#'s in full voice convincingly, and even sang semichorus for the Vaughan Williams mass, where the bass gets a totally unaccompanied and exposed solo in the credo with the E abl=ove middle C.

I've also discovered that I have a middle voice! It's very quiet at the moment, but it's definitely distinct from falsetto and has a much better tone, and can get up to about tenor C (I can get soprano C in Falsetto, but it ain't pretty...). I want to know if anyone has tips for (in order of priority):

1 - developing my middle voice, especially making it louder, but also improving transitions from full voice (right now they're pure awful).

2 - Increasing further the upper range of my full voice without doing anything that might strain it

3 - Increasing my full voice's lower range (it can't involve smoking )

thanks!