Nonne est Segnius adverbum comparativum? (segniter, segnius, segnissime). - Yes, that is correct.
Excepti ? Legati Albani absimiles Legatis Romanis sunt? Legati Albani blande ac benigne, libenter regis convivio…? “excepti” here means simply “having been received by Tullius…” (from the verb “excipere”). And “interesse” is “being present and taking part in” (contrary to “adesse”, I guess, which seems to mean only “to be present” without any connotation as to activity).
Romani priores (ante-Albani?) res repetiverant et… Te Romans were first to demand the return of what had been taken ? I don’t know the rest of the story (and therefore do not know why the pluperfect is being used), but I guess that it means that the Romans had made the same demands (“repetiverant” from “repetere”) as before (“priores” belongs to “res”), the king of Albans denying their demands, they then declare war for the 30th day.
To the third question, a passage from Adam’s Roman Antiquities may be of interest:
Many thanks for your detailed reply Carolus Raeticus and your encouragement!
As to the third point I think the point is that the Albani are slow to move things along, preferring to party at Tullus’ court, and that the Romans are first (priores) to make demands for redress for incursions to their territory etc… Hence I couldn’t figure out how ‘priores’ could apply to ‘res’…
Both sides had sent ambassadors to each other to demand restitution for mutual cattle raids. While the Alban ambassadors were wasting time being entertained at Tullus’ court, the Roman ambassadors who had gone to Alba had already made their demand on the Alban king, had been refused, and had declared war. Tullus (who was spoiling for a fight) engineered this sequence of events: he wanted the Romans’ demands to be refused by the Albans (as he knew they would) before he refused the Albans’ demands, so that he could claim to have justice on the Roman side in declaring war on account of the Albans’ wrongful refusal of the Romans’ rightful demands.