Ciao! I hope it's okay but I have a very specific request. How would you say something like, "Great! Let's go!". Like you just made a new friend and invited them to come somewhere with you. (Also, if you have any references for the Milanese/Lombardi dialect, I'd appreciate it!)
Ciao!
This is you speaking after they agreed to come with you, right? If so, I'd go for a literal translation like "Fantastico, andiamo!" or "Grande, andiamo!".
Idk if these days there's a great usage of the milanese language in our everyday life tbh, I think it's very much more used its "accent" (also as a joke/stereotype), or as we call it "la gorga": the accent that makes you sound like a good "baĂĽscia"! -jk, milanesi friends :P (as a reference for this way of speaking, think about Renato Pozzetto or Diego Abatantuono -who took up the gorga very well).
Anyway, you can find some songs on youtube that are typical of Milano and Lombardia (here and here, a couple of collections. Memo Remigi is a famous singer who used to sing, at times with Ornella Vanoni, in milanese. Nanni Svampa and Jannacci, Cochi e Renato, they're all other good samples of the milanese culture in music and theatre), or you can check infos on wikipedia especially the phonetics part (check also the lingua lombarda page you find linked and the literature one too as it may help). I would also suggest to rely on @urluch-in-dla-nebia as they're all lumbaard and use their language a lot in their posts + share a lot about Lombardia's culture and traditions too. I also reblogged something from them here and there, you can search for #lumbard on my blog if you're interested or just check their blog.
Lombardia is a pretty wide regione in Italy so if you want to know more about all the dialects/variations of the lumbard minority language, keep in mind that there can be differences with milanese if you move to another provincia (eg. Cremona, Brescia, Pavia...) or just take a few steps away from it. TBH, this is true in each regione here, also the smallest one: every comune has its own variation of the regional language, no matter how close or far they are from a bigger city. It depends on the bigger language influence they had to endure during occupations in the medieval era or before/after it.
I speak a bit of lumbard and understand it, but I'm not Milanese or Lombarda: my hometown is just very very close to Lombardia's borders and part of my family's ancestors come from there too. Here we speak a dialect that is more similar to Milanese than to the regional language we are supposed to speak.

















