[dmb]

Answering in reverse order for reasons that will become obvious ;-

3. Adox information on R09 states 'When using high dilutions and small developing tanks please make sure to apply on each film 35mm or 120 at least 5 ml of concentrated devloper.'

The next two answers depend on the actual rather than mimimum volume requirements of your tank.

If you have something like a Paterson which will take 120 and 35mm then the bottom of the tank says 290ml for 35mm and go on through 127 (mine is an old tank) up to 500ml for 120 film. These are the minimum volumes needed to cover the film. So in a tank like this there is room to use 500ml for a 35mm film. Other smaller tanks may not be able to take much more than the recommended volume and a) not overflow and b) allow enough room for initial agitation.

So if you can use 500ml of solution then

2. Mix would be 5 + 500 ml (for ease of measurement)

1. Put all 505 ml in. The slight extra will not make any difference.

If your tank won't take 500ml then you may need to move to a 1 + 60 dilution ( 5 + 300 ml ) that may take your film a little beyond 800 you might have to experiment. (Edited to correct maths - duh - not had my coffee yet)