When I'm representing someone I always do so by telephone, it is very rare that a case is complex or important enough to warrant a personal attendance.
The council is not required to provide any evidence at all prior to the tribunal stage.
The council should provide an evidence pack prior to the hearing, but the tribunal will give an appellant up to two reschedules of up to 28 days each, no questions asked. This being the case, if you get the evidence pack from the council less than two weeks prior to the hearing, I'd just call up the tribunal call centre and move the hearing back 3 or 4 weeks, so you don't have to prepare in a massive rush.
The discount is gone, any appeal to the tribunal is against the full penalty. The discount is offered for those who are willing to accept liability and who thus save the council the trouble and expense of having to fight a tribunal appeal, if you could appeal and still pay the discount then everyone would appeal everything regardless of merit.
Do not rely on the post, check the tribunal portal once every few days to see if the council has contested the case. The digital version of the evidence is easier to work with so my advice is that if you get a copy in the post, throw it straight in the bin and download the PDF version from the tribunal website.