And the population of the Albans and the Latins was excessive: to which the shepards also had to be added
"were added" or "the shepards added to their numbers" instead of "had to be added"
who altogether could easily accomplish hope
little Lavinium were going to be[?] in comparision to that city which was built
Lavinium and Alba were going to be little in comparision to the city which was (about) to be built.
Quoniam gemini essent nec aetatis verecundia discrimen facere posset,
Since they were twins, and no distinction could be made on account of age,
Palatium Romulus, Remus Aventinum ad inaugurandum templa capiunt
Romulus occupied/choose the palatium, and Remus (occupied/chose) Aventinum, sacred places, so they might take auguries, (continues below)
ut dii, quorum tutelae ea loca essent, auguriis legerent qui nomen novae urbi daret, qui conditam imperio regeret,
so that the gods, whose watch concerned those places, choose by auguries, who was to give name to the city, and who was to reign the city, once built, with authority.