400' is a great size. It's actually a bit on the long side for most cave but useful for OW wreck dives and stuff like that. It's also enough to do the catacombs the long way. I recommend you skip the safety reel and get 150' and 50' spools. The 150' spools are great for safety and the smaller 50' perfect for most jumps.
Try to get a good primary reel. It all comes down to what you like better but I'm a big fan of the Light Monkey/Halcyon type. Easy to control friction.

