Calumet is at 22 W. 22nd Street. To get there take the #1 train from 59th St./Columbus Circle station to 23rd St. The #1 train runs down 7th Ave. in that part of town, approximately 1 1/2 blocks west of your destination. Adorama is only four blocks south at 42 W. 18th St. Both stores are on the south sides of their respective streets, between 5th and 6th Aves. B&H is at the corner of 34th St. and 9th Ave. To get there, take the A, C, or E train to 34th St. The A is express and the C and E trains are local, but that doesn't matter. 34th St. is only a few stops away. The station for these trains is on 8th Ave, leaving you one block east of the store.
Navigating midtown Manhattan between 14th and 59th St. is dead easy. All the streets are in a grid pattern and intersect at right angles. The street numbers increase as you move further north or uptown. Avenue numbers increase from east to west. Broadway is an exception because it traverses the island diagonally from northwest to southeast. I crosses 8th Ave at Columbus Circle, 7th Ave at 45th St., 6th Ave at 34th St., and 5th Ave. at 23rd St. There are a few avenues on the east side, which lie between 3rd and 5th Aves. From east to west these are Lexington, Park, and, above 23rd. St., Madison Ave.
Any of the stores mentioned will have film for you at very competitive prices. I can't help you with places for processing it since I do that myself. Others here have far better information than I about that. However, one or two passes through the hand baggage x-ray machine should not be a problem.