Hi Caroline, don't worry about being a girl - its an affliction that my wife also has to live with (aside from me!!)....
The exhaust grating noise could be a couple of things, as you say it could be the heatshield that sits over the manifold, if this is the case its easy and inexpensive to replace.
I have just replaced mine (as it split and rattled/grated) with a better quality one than FIAT supply, I bought mine off ROBOT here on the forum but a believe he bought it from eBay, if you drop him a PM I am sure he will forward you a link.
Its easy to fix and should not take your mechanic more than 10 mins, its only 3 x 11mm nuts holding it on, this picture shows where they are located.........
The other possibility is that the wire mesh covering the vibration absorbing section of your exhaust has corroded, poke your head under the car and if your exhaust looks like this it could also be causing the noise...........
The handbrake cable is a pain in the bum, not because its difficult just 'cos its fiddly. It is adjusted from underneath the handbrake lever so your mechanic will need to remove the trim on the centre consul to get to it. FIAT actually recommend removing the handbrake assembly, adjusting the cables and then re-fitting it but that its a royal pain. He should be able to do it in-situ but it will take time as you can only adjust the nuts about 1/2 a turn at a time. Once the handbrake trim is off it looks like this...............
Note, when I took this photo my handbrake was out of adjustment hence the reason the bracket holding the cables is not straight, it should not sit like that. There is no further adjustment under the car so if he goes looking for it (as I did) he will just be wasting his time and your money!
Hope this helps!!