All three of your rules (swap blanks, swap single letters, and allow consulting the dictionary) are listed as official alternative rules in my Scrabble rule book[0]. We've always allowed use of the dictionary (as a new immigrant from northern Europe, it was one of the ways my grandpa learned English), but we just talked about adopting the letter-swapping rules the next time we play.

[0] I have my late grandpa's "deluxe turntable" version from the 1970s, before it was owned by Hasbro, and my folks have an almost identical one from the 1980s (Hasbro-branded). I believe both rule books have these alternative/house rules.