Picture 3 is the front crossmember and indeed it doesnt look great ...if you can poke a screwdriver through it ask a local welder to see if he can patch it because the rest doesnt look too bad .... and if you catch it early enough, the rust can be cut out and patched ...... then waxolyed and will be good for years...
IF it can be patched your looking at about £20-40....... IF its too rotten you can get them replaced for about £100 (garage in Weston quoted me that about 2 years ago)
NOTE .... Some garages will take the p ..... some quote £2-400 ... walk away.
You can buy a new front cross member on fleabay for about £20 and do it your self .... also get two spot weld drill bits because there are about 30 odd spotwelds and the proper drill bits will save you ALOT of time..... took me about 3-4 hours with lots of cups of T ... The new crossmember just bolts on .... i didnt have mine re spotwelded although you are meant to officially .... but i put a coat of waxoyl on mine so no one will ever know its not spot welded ... and to be honest the crossmember is so flimsy i dont see what difference a few spot welds would make .
Other than that and if the sills etc are all as clean .... NOW is the time to buy the waxoyl and give it a damn good coating ...... and if you get the crossmember done your looking at another 5-10 years IF you give it a yearly treatment..... (of course thats as long as the dreaded rust doesnt start from the inside out)
Whether you replace or patch that crossmember IF its holed .... it needs to be addressed and it will fail an MOT if its holed or very weak..... and make sure you coat with waxoyl ...... long term it will save you £££s.
Looks like a very tidy car overall and ALL cross member rust ...unless you wax treated them from new or live in the Sahara.... and exhaust do look like that...might be good for another 2 years .... .. change it when it begins to blow lol