To answer the primary question: "sure, there are Rachmaninoff pieces you can handle!"
He has reputation to write difficult pieces but in fact let's put it this way "he has nearly not written any easy piece". Also, taking into account the pieces you are currently dealing with, you can easily try most of Rachmaninoff pieces (however, you should more or less dedicated depending on the piece). Sight-reading is a must for his pieces as they are quite thick in structure, and sometimes tedious to read. So... go!
About the not-so-hard preludes:
Op 3 No 2: you can easily deal with it. It will introduce you to big chords in the A section (not necessarily a problem if you have small hands, it is just a matter of position since it is quite slow) and multiple lines in the B section
Op 23 No 1: easier I think than Op 3 No 2 (I never played it though)
Op 23 No 4: same
Op 23 No 10: the easier of his set of preludes
Op 32 No 5: if you are familiar with cross-rythm then it can be easy... else it is quite challenging. You can still give a try to the beginning and the section where the left hand changes and the right becomes faster. If you do survive, then it is easy

Op 32 No 12: is harder but should be manageable. It is not slow but t is not its difficulty. The problem here is its variety.
Do not think 32 10 is easy. It is very challenging for coordination in section A, and musicality in section B + a hard cadenza.
You can also look at various other pieces by him that are really nice such as Etude-Tableaux (some are not devilish, 39 2 comes in mind), Lilacs (although hard), or his Moment Musicaux (but forget about the even ones which are very difficult... look at 1, 3, 5) and I am sure I forget a lot of other pieces.
About the pedal: Beware not to use the pedal too much... It can become really blurry! I think I myself very rarely (never) let the pedal pressed when starting a new measure... and I should probably be ranked as an average amateur using too much pedal.
An example of careful pedaling is in Op 23 No 5 (you surely are familiar to it), it should be really accurate in section A and should really help building the Russian march theme. You spend most of the time with the pedal depressed here.
In fact, I know only one piece where Rachmaninoff wrote pedaling: Moment Musical 4... and I do not follow it (but I am a very bad example).
I think the best edition is Boosey & Hawkes... but still it is a matter of taste. If you can find different editions of the same piece, compare them carefully before buying.
Don't worry if you cheat the tempo here and there, as long as it is here and there, speed will build up with time!
Nisa