Yes.could these sentences potentially be ambiguous in Chinese? ("I'm getting my hair cut tomorrow" or "I'm cutting someone's hair tomorrow" (if the person is a hairdresser))
I have not ever heard anyone around me saying '絞頭', so yes, I'd have been confused.在北方说剪头也没问题，但到南方说 jiao3 头恐怕就不懂了。
We may say something like, '旁邊推九分, 後面一樣推高, 前面到眉毛, 謝謝.'令我想起北方男生可能会说类似的 “把头推一推 /推个头”。
In Hokkien, it is actually pronounced '嘎淘摸'.楼下说闽语也这么说，是我孤陋寡闻了...
You are right. As a matter of fact, the character '撸' is rarely used in formal writing. (It is most commonly seen in '撸管', '撸貓', and '把頭髮撸一撸' in my personal experience.)I think [撸一撸] sounds super informal or dialectal.