i'm not too well up on compressors but i found the cs3 pretty noisy, so you might want to avoid that one. Also, i'd personally rather use an OD than a compressor to get that chug, but that's just me. the other thing is if you're sure you're buying an OD anyway, you might as well get it first to see if it covers both your od and compression/chug needs.
ce2 clone is a good call by juan solo. i have the tonerider one, which i don't think is a direct clone, but which is very closely based on one, and it's very, very nice. you could pick them up for £50 a while back from dangleberry (i paid £67 IIRC :shock: ), but they seem to have stopped stocking them and the tonerider pedals seem to be hard to find now for some reason. or you could get the mooer chorus for like $44 from china, it's supposedly a ce2 clone. I haven't tried that one, but the mooers i do have (aside from the fuzz, which i think is faulty, to be fair) are very nice and the chorus seems to be one of the ones which has a good rep.
overdrive, it's really up to you. Your blackstar is (far as i'm aware) hybrid, so you'd want to be sure it takes ods like a proper tube amp. That's not to say it won't- plenty of solid state dirt pedals stack really, really well- but i'd check out that it'll work first before spending any money, kind of thing. just in case. the other thing is, if you're thinking of the blackstar pedal, i think the BS HT amps' preamps are based pretty closely on their pedals (or vice-versa), so you want to be sure you're not paying for something you more or less already have in your amp.
EDIT: no clue on the delay, sorry.