I have used a pole a few times (belonged to a neighbour who has since
moved house). However, I have just bought a pole and it came with 2
elastics 1 gray and 1 day glow orange. They were in the base of the
pack, no anchors, plastic bush or stornfo (or whatever).

Question 1 is, how do I know what elastic rating they are?

The gray one is very strong and quite thick (I cannot snap it) so I
assume it is a high rating.

The pole is a 11m Frantic.

Question 2 is, when elasticating, how much tension do I put in it?
And, how will I know I am at the right tension? - initial thought is
to use a bag of sugar to pull it out a set length.

Question 3 is has anyone any idea who makes it?