I think you might have to have booked you return flight before you go.Immigration usually ask for this.Pick an Airline who charge the least to change arrangements as plans can alter.
Try not to look touristy I have spent months hiking and traveling over there and never had the police speak to me.
Sew $20 or so in a coat lining you will always have cash then.They will laugh at strange credit cards and our driving licences as ID, least they did in Tennessee.You would had thought I had just made them, and walking in to a drive thru bank was just freaky.
How are you traveling about. List looks OK to me. I wouldn't overthink it- they have some of the best outfitters and shops in the world over there. I would hazard a guess your plans will change as your trip develops.
I did 39 states on one study trip of over five months using Greyhound buses.I traveled till I had had enough and and then hopped off and hike/camped till I was refreshed.
Like a lot of subjects on here it depends on your trip.If you are an a multi week trip especially abroad you need things to work hassle free.
I have used the in line Parky set up in gravity feed mode which is great as at night and as you are making camp doing other things you can be you filtering 2 or 3 litre or more for immediate and next days needs.I did this but the flow was soon dismal, some my error as I didn't pre filter enough( even though I was looking out for moose poo in the water) I did not take the tap connector to enable backflushing which all that was required to improve the flow.I resorted to Aquaventure tabs for the rest of a long trip. That system is weighty/bulky for me so according to conditions and trip I now either use the Sawyer Mini or the Travel Tap but I have had leaks at the thread with the TT though that has been solved with an new gasket. I favour the Sawyer now and take Aqua venture tabs as well.
When filtering is hassle free you drink more which is good