Congrats to the fledgling Eagle from a 25-year Eagle Scout and 33-year Scouting veteran. Bravo! Well done! Welcome to the brotherhood.

Regarding the kilt and the Boys Scouts of America uniform: There is nothing in the Insignia Guide (the uniform regs) regarding kilts, but (per my Council office) since they are not listed as acceptable uniform attire, they are generally not allowed except by special permission, for specific events. (I'm allowed to wear my kilt with my uniform shirt when I'm piping.) Venture Crews are a special animal, as they are allowed - by charter - to select their own uniform. When mixing with other units, however, they are encouraged to wear the 'standard' Venturing uniform (the forest green shirt and gray trousers/shorts).

Some people ignore this and wear a kilt anyway. (It's easier to ask forgiveness than permission.) There've been other threads on this elsewhere, and I've had my say there, so I'm not going any further down that road in this thread.

Regarding the MacLaren tartan: EHCAlum got it pretty close. Gilwell Park is the home of Wood Badge. (Wood Badge is the premier leadership training course for Scout leaders the world over.) Every Wood Badge course, regardless of its physical location in the world, occurs "at Gilwell". The site is in Sewardstonebury, Epping Forest, close to Chingford, London. It was purchased by William de Bois MacLaren and donated to the British Scout Association to provide a campground for London area Scouts and a training site for Scout leaders. In recognition of this grand gesture, Lord Baden-Powell (the founder of Scouting) put a swatch of the MacLaren tartan on the Wood Badge graduates' neckerchief.

Regarding hiking clothing: unless your unit requires you to be in uniform while hiking, wear what you'll be comfortable in. (Technically, there is no 'Class A', 'Class B', etc. in Scouting - those are military shorthand terms. The correct terms per the Insignia Guide are 'Field Uniform' - the khaki/tan shirt and green trousers for Scouts or dark green shirt and grey trousers for Venturers - and 'Activity Uniform' - same trousers as before but any Scout-related shirt.)

OK, time to stop talking...