My reasoning for the HE was thinking more short term: NY (in 6 turns) would have 24 hammers, pumping out knights every 3-4 turns, grenadiers every 4 turns, and trebs every 2-3 turns. (I'm playing 2.08 but they're worth less on 1.0, right?) NY also has more forest tiles to work and once we get RParts it'll have even more hammers.
A navy is something we won't need for a while. However: a drydocks, factory, and forge (+100% or 125% with power) would give us comparably decent build rates in the two good navy building sites on the continent, namely Bibracte and a rebuilt Georgovia (if built on the wine). This allows us to have more good cities building land units faster, now, (which we will need more of anyway) than saving it for later when we can still pump out battleships (if we even get that far!) at around 4 turns a piece w/out the HE. Right now we need land units, and lots of them.
As for chemistry, rifling is over 20 turns away, whereas chemistry is around 6-8 turns away. (I don't know how you're going going to balance the slider so I'm speculating.) I still find Uncle JJ's advice interesting, mainly because I never run Nationalism and it sounds like I need to try it sometime. (Old habits die hard)
Of course, it sounds like you played the round already so maybe this advice is totally worthless....
As for "foreign policy" matters, Saladin's pretty much dead weight and killing him shouldn't take more than the 10 turn peace treaty we have going. He's cautious with Shaka and Stalin, (but friendly with brennus) so hopefully no defensive pacts will come out of those relationships, so maybe he's a non issue. His relations with Brennus means we'd have to either kill him now or wait until brennus is almost gone, since he would most likely vassal with brennus.