Hoop Pine T&G over existing

Hi,

Have read most of this forum, got tons of info but thought I would be ask about my task.

1905 Workers Cottage/Queenslander with Hoop Pine T&G, good joists, restumped some time ago (<15years i think). I have made lots of repairs to the existing floor but ended up with more new wood than I thought I would and it is very patchy. Some of the floor is original and some work has been done some years back. Some wood excellent, soome poor.

Anyway I want to lay a new floor over this. Have considered all options and decided on this.

From this forum I have got....

1. New wood same way as old with centre of new crossing old joins (ie start first board half way down old).
2. Use T nails long enough to go into hardwood joists (boards are 20mm so at least 50mm nails.
3. Use adhesive.
4. Already removed skirting and most doors dont need shortening/planing as the old carpet was really think and it already has been done.

Questions

A. Some say new boards at 90 degrees but beware of saging betweern joists. Which way?
B. Exactly what nails and suggest nail gun to buy/rent
C. What adhesive and where do you squirt it?
D. How do you gap the boards? Should someone just push them together and then nail or is there a certain pressure, etc?
E. Suggestions for places to buy timber. It retails for about $10m but for a house load I would expect less??
F. Should I just get someone in to do it? Suggestions on who in Brisbane? I would welcome direct responses to this as well.

Thank you very much
Scott