Not sure what I'm feeling

Impressive progress for only having the aneros a week.

There are times I feel slight orgasmic sensations from my prostate radiating to my lower abdomen. Are these p waves?
That sounds about right. Those feelings start out small, but can build to unbelievable intensity. So just explore them (or any similarly subtle feelings). As you found out, there's always the temptation to try and make things happen by calling on your existing knowledge of masturbation. But allow your aneros session to be a thing that has a nature of its own. You don't know how it builds or where it goes until you've already experienced it, so pushing it in any particular direction tends to not work.
I'm confused about anal contractions and kegels, Should they be held as long as possible? Done in series? Constant tension?
There's no set rule. Just do what brings pleasure or what feels right to you at the time. A lot of people have success without doing any kind of contraction at all. So don't get hung up on it, manual contractions are just a tool, it's up to you how you use it.

It's not an entirely mechanical process anyway. With traditional masturbation you can be mentally checked-out or distracted and still build up that energy by stroking it, but this is different. You have to throw away the old rule book, which really is easier said than done. Treat it like you're aiming for a new kind of orgasm, it'll help you stay on track and avoid those times when your brain says "Oh I know this feeling from traditional masturbation! Let me try these tricks I know".

I could go on and on... but generally I'd say "explore the new". Suspend your need/want for a traditional release, at least during the session. You can always have a normal orgasm at the end of the session, but for a time, let the aneros teach you new things. The line between familiar sensations and familiar solutions is a difficult one to walk. But you learn with practice.

Well said @Clenchy!

I'm confused about anal contractions and kegels, Should they be held as long as possible? Done in series? Constant tension? Any advice is helpful

That's indeed up to you. The most important part is that you don't clench with force! Unlike the traditional approach, fast movements and big muscle contractions are counterproductive. Subtle contractions will bring you much further.

Well said @Clenchy!

I'm confused about anal contractions and kegels, Should they be held as long as possible? Done in series? Constant tension? Any advice is helpful

That's indeed up to you. The most important part is that you don't clench with force! Unlike the traditional approach, fast movements and big muscle contractions are counterproductive. Subtle contractions will bring you much further.

I think this is very true, even when the big contractions seem to make you think you're going somewhere. Its also why i personally feel larger devices are not as good, at least for me. There needs to be some movement, subtle, but some

Thanks for the reply. The feelings feel nice. I don't quite know if I would describe them as sexual. That's why I'm confused.