I'm not sure if you know how betta genetics work, but it is complicated and can be much harder it seems to get the colours that you want. That female blue veilteil has very dominant genes. It is highly likely that all fry will be blue, and there will be no dalmatians or peach coloured fry, let alone a combination of the two.
"Dalmatian" in itself is not clearly defined, so it is hard to say what kind of genes your male has. He might breed true and he might not. So even if you'd get two bettas sold as peach dalmatian, unless you bought them from a trustworthy breeder the odds are high their fry will be all sorts of different colours. And some colours (I'm not aware if this is true for dalmatian or not) don't breed true which means the pattern just appeared by luck on the betta you breed with, and its fry has about the same odds of getting it (which is usually quite low).
All in all this pairing is pretty sure to give you solid blue veilteils nearly 100%, which aren't worth much.
In any case
breeding bettas to make money is a pretty pointless endeavour, it is almost impossible, especially for someone who breeds as a hobby and does it small scale. If you want to sell your fry rather than give them away you should probably not breed with veilteils, which are worth the least out of all the tail types and are commonly available in all large and small pet stores for a cheap price.
I'm not really sure how the large/XL gene works, so I'm not sure if crossing large x XL guarantees large offspring (I believe it's only an increased chance with a large portion of fry normal size, but I'm not 100% sure).
The recovery process is pretty much like conditioning (warmth, isolation, frequent feedings with 'power food') because you have to get their strength back up. Dosing with a mild antiseptic or something similar (like
methylene blue) is advised to keep their injuries clean. Do lots of
water changes to keep the water pristine for this same purpose.
Most betta breeders I know have 1/4 - 1/2 gallon plastic containers they put on heat mats or in heated rooms/cupboards. The containers cost a few cents each but it is labour intensive as you have to do daily water changes on all of them.
I realise you are quite invested already, but I wouldn't really recommend betta for your first fish to try breeding with. The spawning process is pretty violent (you may occasionally lose a fish) and anabantoid fry are all pretty vulnerable and stay very small for quite a long time. It is easy to screw up in their care and kill your entire batch. Many other species with larger fry, or fry with parents who show much larger degrees of broodcare, are much more forgiving of mistakes. It would be a shame to invest money and effort to lose all your fry after a few weeks. Moreover (as you've already noted) separating all of the fry is labour intensive and costly.
