Looking at the pic looks like you need a new chain with the slack even without the tensioner,but as for fitting without splitting chain are you sure there is not a split link.there are 2 types of pads 1 open and 1 where you would have too split the chain and feed through it.As for chain size should be 520.pitch
Looks like your bike has later forks fitted. You can find. rear mudguard here. https://2bbikes.com/Webwinkel-Product-136112255/2003-ed-rear-fender-red-txt.html
Check pilot jet ,there a bugger for clogging up put a 17.5 in my 125 upgraded to 150cc used to be a bugger to start when cold,could be 10 mins or more trying to get it to tick over also check your choke tube there is a small hole below the plunger and i mean small.once i cleaned that out fires up first kick 3 turns out on mixture as said earlier spot on now.Choke on now starts first kick and no more coughing and spluttering for 5 mins while it warms up.
As above should be 97 as for price it's what someone is willing to pay,but big difference between 97 and 2003,i know there used to be a bit of a cult following of these,but i had 1 and sold it within a week just couldn't get on with it.