1. As with so many other things English, I doubt that there is a uniform rule; historical accident probably played a larger part than logic. Before the Reformation, the advowson of many urban parishes belonged to monastic houses. Like their rural counterparts, these advowsons would have passed into private hands along with the other monastic property when the monasteries were dissolved. To the extent urban advowsons were held by the diocese, by collegitate bodies or by other foundations, they would continue in those hands. As London grew and the surrounding rural villages were urbanized, advowsons in places like Bloomsbury, Soho, Marleybone, Bermondsey &c would continue to be owned by whomever had held them before urbanization. Query whether the Livery Companies owned advowsons in London, since certain parish churches in the City were associated with certain guilds?

2. Iirc, there was some kind of church rate. There was also a legal duty to serve as churchwarden when nominated or to pay a fine to the parish if one refused to serve. During the 18th century, I have read, the vestries of the London parishes where the City's Jews lived made a practice of nominating well to do Jews as churchwardens in order collect the fine.

3. That's an interesting question whether urban parishes owned the equivalent of glebe land. If they did, the rental income from it would be quite lucrative. I think that even today the Church Commissioners are among the largest urban landlords in the UK.

4. I think I know where to find the answer. In 1836, tithes were commuted by statute. To implement the act, a comprehensive survey of tithes throughout England and Wales was made, parish by parish. The whole 1836 survey is available on CD-ROM or from the British Library. A Professor J.P. Kain of Exeter University seems to be the leading authority on it.