Absolutely. Always wear long pants on planes. Alcohol pads might be a good idea to clean vinyl seats too.
Yes. An airline seat would be one place you could get lice. This is called vector transmission. Vector transmission occurs when lice are spread through inanimate objects. For instance the lice can be on brushes, combs, hats, headphones, scarves, sweaters, coats, bedding, towels, upholstered furniture, carpet, stuffed toys & seats in a variety of areas. Bring a lint remover with you if concerned.