bottom feeders

Wafers will be 'just the job' for most of the fish you mention - the big exception being the Rummy-Noses (which will still try to have a nibble) - the Rosy Barbs will also get in on the act, but these will tend, as they get larger, to 'hog' the wafers (mine used to) so some more conventional food like flake or granule food fed at the same time will help to distract them and the others might get a bit better of a look-in on the wafers.
The Hikari wafers I use are extremely hard and take hours to break down to a stage where the Barbs and Tetras will be able to bite chunks off them and I always put in a couple (or three) after lights out as the bottom feeding fish you mentioned will all carry on feeding after dark, you might want to consider doing this as well.

John
Sorry, I meant to mention the Clown Loaches, I have found that these do often tend to 'bed down' for the night around lights-off time but these are pretty omnivorous anyway and will eat almost anything which is put before them, they can make quite short work of the wafers too.

Cooked peas (I put a few in the microwave on full for 30 seconds from frozen then peel off the outer skin) are a good and nutritious food source for lots of fish, I even find that 'carnivorous' fish like Angels - and many other Cichlids will also eat some too...actually, I have some types of Dwarf Snakeheads which eat almost as many as I put into their tanks!!!
So, yes, all your 'bottom feeders' will eat Peas to some extent. If you want to try them on the Corys my way of giving peas to them is to slightly crumble the Peas between finger and thumb which makes them more manageable to the Corys. I will add that the same information applies to Sweetcorn too - although be prepared to remove either if your fish do not 'take' to them - try a little at first and remove whatever isn't eaten after a couple of hours, remembering to give them less next time.
Your Otocinclus and Pleco will also enjoy a slice of something like Cucumber (you'll need to weight it down as otherwise it will float) but remove any uneaten after a day or so, it will start to decompose, and you don't want that!!!. Another good piece of advice I was given is to use a potato peeler and peel off the green skin, some growers aren't averse to using insecticides and sometimes the residue of this can be harmful to fish gnawing on it, so I always skin whatever I give the fish first, better safe than sorry! I suppose you could buy 'organic' Cucumbers (but I have my doubts about those too and would still peel them to be on the safe side.
For clarification, only peel the section you have cut off to feed to your fish, the remainder can be left with skin on until you're ready to use it (it keeps better like that).

Sorry, I forgot the Clowns again! - they will also eat peas, sweetcorn and Cucumber, clicking away madly as they do so! - Well, mine do.

John