Yes, I am not sure why the one strap. Every one of my basses has a strap - I would find it irritating if they didn't, they are different sizes so would sit in different positions, and more importantly they are different colours, how could one strap cope!
The elecrical thing, it seems to be that venue that specifically has bad electrics, its outside at an end of cable run and testing it with my power tester, the voltage is 209v with 1-4v N-E, but otherwise is fine, and obviously it goes to say when I gave him my wireless, I connected by cable and had no issues - in fact I gave him my cable knowing I would have no issues, so said he needed to get his power supply checked - whatever bad thing is happening in the power of the venue, should't be getting to you.