Scojo, one would need a large book on this, and afaik there is none, at least not about the Luftwaffe ... I read anything I could get about the Luftwaffe-recce-operations, the quality of sources differ VERY much. Anyhow, one respectable source on this:
First of all: in general there were two types of recon, long range photo-recon for strategic aspects, against an air defence system mostly flown as high and / or as fast as possible, often at night using flash-bombs. And tactical recon often done visually from slow and agile planes.
* Were recon planes ever escorted?
Rough conclusion: long-range recon very rarely, tactical recon sometimes
- Were recon pilots attached to air groups, ground forces, or both?
Germans had them organized in squadrons (ca 12 planes), long-range targets usually were ordered for a single plane via Luftwaffe high command. Short-range squads were associated with a larger army structure like an "Armee" or a "Korps" and got their individual orders directly from the army HQs.
- What were the reasons for having dedicated recon aircraft as opposed to retrofitting aircraft such as the 110 which would also have armament?
High speed, very high max. altitude (check Ju-86 P), very long range and enough film material to cover large areas for the long range recon planes. Tactical recon often tried to "sneak" along the front line very low, maybe at the clouds base, find a gap, sneak around behind the lines, used binoculars often. So it was good to be agile, not too fast with a good visibility.
- How integral was aerial recon with artillery?
Very different, for the Luftwaffe is was an option, but not a "common" procedure along the front lines. I read about it especially when the high command focussed to conquer important single target areas like Sevastopol. Away from that kind of focal point it might have been rarely done. But that's really difficult to say because the sources are scattered. For the western allies in 1944/45 it was a common, day-by-day procedure. The Soviets used it, too, don't ask me about the extend. Another reason to add on the pair Po-2 Kukuruznik and Fi-156 Storch to IL-2 BoX ;-)
- How far into enemy territory would dedicated recon missions fly?
Several thousand km for strategic aspects or 10 - 20 km to gather unit-level-information about numbers and types of formations at the front line.
- Was night time recon a thing or very popular?
For the Luftwaffe in the West and Med from 1942 on often the only way to do any long-range recon at all. The few recon-jets changed it somewhat in late 44. The loss of aerial superiority forced the Germans to use fast Me-109 recon-planes for tactical recon more and more, since any other planes like Fw-189 and Hs-126 had no chance to survive more than a few sorties. In contrast the western allies did much better with several well suited fast planes like Spit, Mossie and P-38. Haven't seen that much about the Soviet recon operations, in short: not that advanced as the western allies, but the usually thin German air cover gave them lot's of operational freedom to become very effective.
PS: another large topic is the maritime recon, not covered here