Unfortunately, there is no single answer to any of those questions.
It depends on what type of rooftops you intend to walk. For me, I had a Telesteps 1600ET (used 90% of the time on interiors and exteriors); 22ft US made Little Giant; Werner 32ft extension (All were rated Type 1-A).
Flir is the most popular Mfr. Type LWIR microbolometer. <= 50mK NETD, ~ 25° FOV, 320x240 min, adjustable focus. Better to ask where to get qualified training to know what service you intend to offer before venturing into equipment selection (like saying to a diverse group of professional photographer “I want to be a photographer, what camera and lenses should I get”).
Try several and see what is most intuitive for you while meeting your minimum core requirements, business process integration and field usability.
Delmhorst, Protimeter, Tramex, Extech account for the vast majority of professional-grade meters. Pin, capacitance or combo depends on your use. Model depends on your use and whether you expect to use accessories like deep wall probes, extension probes, hammer probes, etc. I owned and used Delmhorst BD2100 pin type (with mentioned accessories), Delmhorst and Protimeter capacitance type and Tramex Leek Seeker (for commercial roof work)
Begin with using the MB Search feature as these questions have been asked hundreds/thousands of times already. AFTER you do so, come back and discuss your specific questions of those that have actually used those specific Brands.
1: Telescoping Multipurpose Ratchet Hing Ladders.
Length. Personally, 13’ and 17’ foot gets me onto most roof surfaces using a balcony.
*Note: Before you run off to buy a long ladder, mounting roof surfaces is not required. Purchase a good zoom camera.
2: 6’ foot fiberglass, non conductive, step ladder. I rarely enter attics. I purchase a good zoom camera. My first piece of professional equipment.
3: If you are new to inspecting hold off on professional thermal imaging equipment.
4: Personal choice. All free to try. I use Carson Dunlop Horizon. No fluff. 400 pages at the back of the report links to everything you reported on.
5: Manufacturers. Tramex and DelMhorst. You want to measure deep in a substrate. Wood, Drywall, Laminate, Masonry to start.