Did the pre-Islamic Arabs...practice circumcision?

Yes. This seems to have been widespread to the point of near-universality among males and was also practiced on females. The Arabic word for the practice "khitan" is pre-Islamic, and we also have pre-Islamic words referring to the un-circumcised. The practice of circumcision is also mentioned in pre-Islamic poetry.

A second century AD Syriac commentator, Bardaisan, noted upon the conquest of the Nabateans (of northern Arabia) by the Romans that:

‘Recently the Romans have conquered Arabia [i.e. the Nabatean territories] and have done away with the old laws there used to be, particularly circumcision, which was a custom they practised’

From Robert Hoyland's Arabia and the Arabs

Moreover, in the hadith, circumcision is included among the "Fitra", the practices so basic to human existence that there are expected to practiced regardless of any specific religious injunction almost as a point of personal hygiene, and which include clipping one's fingernails, trimming of pubic hair, removing under-arm hair and trimming the moustache.

Moreover, circumcision would have been practiced on a religious basis by the extensive Jewish community of Arabia, which seems to have been common in north Arabia and even predominant in the Himyarite kingdom of Yemen.

As a result, I'm not familiar with any objections to the practice.

Did pre-Islamic Arabs eat pork?

I can't prove a negative, but, as I've discussed previously before HERE, the answer seems to be no. Certainly there were (and are) pigs in the Levant and the wider Middle East and Arabs who would have come across and even eaten pork in those locations. But that being said, and I say this as a non-farmer, as far as I'm aware the conditions in most of Arabia are not conducive to raising pigs, and boars are not endemic to the Arabian peninsula.

So in pre-Islamic Arabia, as now, the primary forms of pastoralism related to the raising of camels, sheep and goats, and to a certain extent horses, rather than the raising of pigs or cattle which are ill-suited to the desert.

source wise:

As mentioned above see Robert Hoyland's Arabia and the Arabs

and the Encyclopaedia of Islam entry on circumcision "Khitan."