IMO the spines don't look yellow enough to be P.pachycladus.

The Echinopsis could be E.oxygona or some common hybrid.

whilst the spination of cristate plants can differ considerably when compared to normal specimens of the same species I'd imagine that a T.terscheckii crest would have longer and heavier spination than your plant.

WOW!
could be a Gymnocactus/Turbinicarpus horripilus.
trully incredible specimen.

graft graft graft!

the first one does look Echinopsis/Trichocereus-like to me, but I can't put a species name on it sorry.

I'm very jealous of the myrtillo, its an awesome plant and i've never seen one of that form here before.

G.saglionis or pflanzii.

^ yeah, being an Echinopsis that is likely.

and don't water it immediately after repotting, wait a week or so. and if you repot it now then don't water til spring.

i agree with Tony.

i'll have a few guesses; 1. i thought melocactus but spines are wrong. still I've never seen a Disocactus at a big box store, and i thought they were fairly rare in general. 2. Trichocereus/Echinopsis hybrid. looks like a shorter spined version of T.grandiflora.. 3. Mammillaria sp. 4. Parodia sp. 5....

i know you may consider this cheating or non-puristic but maybe you could graft a few seedlings to speed their growth time to maturity (by many many times!) so you can use them as stock plants for seed production much quicker. Also eliminates the difficulty of culture!

New one is a Notocactus/Parodia, a super spiney specimen if its a N./P.mammulosa.

Grumpy looks to be some form of Mammillaria.

Agree with M.vetula ssp. gracilis for the last one, but it is in need of more light.

Yes, it is in need of more light, as hard as that may be to achieve in the UK.

great work CV!!

I have also done this, with this local butterfly:
http://photos.rnr.id.au/butterflies/Papilio.jpg
Dingy swallowtail or Citrus butterfly, Papillo anactus.
The caterpillars feed on orange tree leaves.