[X] Avernus can generally deploy half of its regular PDF, three quarters of the Helltroopers and Helguard, as well as half of the Battle Psykers for campaign. More can be deployed if the situation demands it. Portions of the militia can be deployed if necessary as well, with the example the use of militia AA regiments to bolster the forces used to take Fjol IV from the Dark Eldar.
[X] Additionally, you note that Avernus has 300 Orbital Defence Platforms and 60 Heavy Orbital Defense Platforms that were mothballed once the Advanced designs were made available. They are Imperial era platforms upgraded with technologies from the Defence Cruiser designs. You are willing to donate them to Fjol IV as a stopgap measure to bolster their orbital defenses until they can build Advanced platforms, provided they can be transported.
(Assuming there are no major and glaring issues that we've missed.)
Looking at psyker choirs, maximum divinatory power for Ridcully (While using only Divination-specialized psykers) is currently at 207 Major Diviners (16 Primaris (Elite/4 Veteran/11), 191 Battle (14 Elite/7 Veteran/170), plus 193 Elite Minor Battle Psykers. With a total power effect of.. Ridcully plus 4 Gamma, 20 Delta (5 Equiv), 27 Episilon(1.6~ Equiv), 146 Zeta(2~ Equiv), 193 Minor or.. about High Beta/Low Alpha in power, up from High Gamma.