In training you can use treats and whatever you like.
In the tests aim for the top. THe whole idea of the tests is to give us the incentive to train our dogs to be 'good citizens'... not just when the envirinment is right and we have trears and training tools...but when things all go pearshaped!
So we want our dogs to be able to walk well without treats, to come without treats.To walk well and ignore dogs no matter what the dohgs are like. To keep atay even if another dog near then gets up and their owner comes in and bellows at them ( as we had on our test as well as other dogs howling barking in relaxed issolation...and they did fail for that )
Basically if you take the test and used treats you would feel bad because any dog will walk ar obey commands for treats and you wpuld fell like a cheat . It's great your trainer is insisting on standards. So you do need to train the dog with treat to get the behaviour you want but then trai to do this without them too so you will be okay for the test. When you can do this you are ready to take the Silver. Good luck.

On the halti I would say trainers should use conmmon sense. If the dog is big and strong and you feel you need a halti just in case then common sense says use a halti. After all no matter how good our dog is at walkng to heel off lead near traffic we still use a lead...just in case..it is common sense not to take unessesary risks. If you are the type of person to want to take unnessesary risks with yout dog you should actually fail the tests because part of the test covers responsible ownership.
After all if the dog pulls you will not pass anyway so you can not 'cheat' by using a halti. If I were you I would put the halter on for the test but point out you always will not be using it for correction. I think people can put half-checks on the dogs which is still a training tool so why shoud the halti be treated any differently.
I always used a standard collar myself for the test because I like the test to be an ultimate target that I am aiming for and my aim has been to walk my dogs on normal collars on a loose lead. With a big strong dog I especially believe in use of voice for control rather then use of pysical force because physically many dogs have the advantage oner us... our advantage is our intelligence and use of training skills. This is especially important when kids are working and training dogs.
The tests are all carried out differently. My silver took three hours because all levels took place on the same night and I kept getting pulled out to be a distraction for the other classes and the room was full of dogs we did loads and loads of heel free all together 1m spaces from each other and I'm sure we did way way more then we did when I took my silver with my previous dog at another club. By thge third hour I was ready to drop! However demanding though in Bronze one dog passed when it clearly should have failed... for the stay they kept trying and tied it up in the end and waited for it to fall asleep before timing the stay which is a total joke and that undermined the whole point of the award! I realy was not impressed as that dog is dreadful and the owner is clueless. If we are going to take the time to tran our dogs those who run the tests should respect our hard work and only pass those who attain the right standard. BUt all said and done the awards are great for encouraging us to train for the basics...I just whish they would do one or two higher levels.
So because thestandards to these tests are so loose and variable you need to decide what you want from the tests... just a certificate with a lapse tester or a certificate and a decently high standard of achievment and go for whatever target is meaninful to you. IMO your trainer sounds good to want the high standards.