i put all those stuff by myself.
no need welding anything cos the exhaust is straight fit. - lambdas are before cats so no need to touch them at all.
for manifold - took me around 3-4 hours to put back everything in.
all u need to do , to prepare urself - I mean to get all parts (B&Q) :P
I did all of those on my drive way.
I would fit all stuff for you with some ur help and few beers :P