I have no idea how he survives because I am sure his dole will have stopped long ago, or should have.
As long as he is meeting the conditions of his Claimant Committment (i.e. actively seeking work by applying for jobs or undertaking activities that increase his chances of gaining work) then he can be receiving JSA/UC for as long as it takes. All the way thought to his State Pension if needs be!
I don't know how that works in practice. For instance, if I worked in Macclesfield and started at 9am, I would have to catch a 7:25 bus after a 15 minute walk to the bus station. Would having to leave home by 7:10 for a 9am start count as an over 90 minute commute?
Last I heard they expected you to plug it into Traveline to work out of it was more than 90 minutes or not. That may have changed but I doubt it. So for your example you'd put your post code in, the post code of your job and set the time to arrive by 9am and see what you get.
If you had a car of course it's a bit different. I would gamble they'd accept a Google maps or similar journey planner result (or if they don't I'd gamble an appeal tribunal would if they tried to sanction you).
My mate was told it is mandatory to attend the appointment, but that he is under no obligation to take any of the placements on offer.
That sounds about right. The appointment will be mandatory (vast majority of Jobcentre appointments will be and I can't off hand think of any that wouldn't be) but, assuming it's the Work Experience programme (which is usually aimed at 16-24 year olds but anyone can take part if appropriate), then yes they don't have to take up the offer of placement. Note that if they do take up a placement then it will become mandatory so if they fail to go to the placement or get 'sacked' then they could be sanctioned.