Firstly note that the TSC Option A Price List can be a combination lump sums (like ECC Option A) and quantities x rates (like ECC Option B). Now to answer your questions:
(1) It will depend on the contents of the Task Order, if it states a quantity for an item then you are entitled to be paid for the actual quantity completed and not the quantity stated in the Task Order. This could be less, more or the same but it's the actual quantity of work that is paid. If a quantity isn't stated for an item and it's a lump sum stated in the Task Order, when the item is completed it's the lump sum that is paid. So in your example you are entitled to 22m2.
(2) You should only do the work described in the Task Order, so the Task Order would need to state that a clause in the Service Information specifically applied to it, or the Service Information would have to state that certain clauses apply to all Task Orders.
(3) Yes, as your Task Order includes the quantities then you are entitled more time if the quantity increases. This wasn't the intention of the drafters, clause X19.10(1) should say Task not Task Order if they wanted you to take the time risk on changed quantities. The NEC4 TSC does state Task instead of Task Order so the answer would be no in NEC4!
(4) You are obliged to carry out the work in the Task and the Task Order should have a detailed description of what this is. The work in the Task is added to the Service Information and you are obliged by clause 20.1 to Provide the Service in accordance with the Service Information. Option A clause 54.1 states that information in the Price List is not Service Information. The priced list of items for the Task are added to the Price List therefore you can see how the item descriptions are irrelevant to what work gets done, its the description of the Task that is important here. NEC isn't like other contracts the pricing information (Price List in TSC, Activity Schedule or Bill of Quantities in the ECC) never specifies or describes the work, it is merely a commercial tool.
Unfortunately the Task Order procedures in NEC3 TSC do have some serious flaws so whilst my advice here might not seem to make sense in places, it's because the contract doesn't always make sense. Simple solution for me (ignoring exactly what the contract says because it's unlikely that your Task Orders are in accordance with the contract or that either party has been applying the contract correctly!) is, if you've done work that the Service Manager wanted, whether or not that is described in any part of the Task Order, you should be paid for what you have done and be entitled to an extension of time if there was more work than was anticipated when the Task Order was issued. Equally if you've done work without an instruction that the Service Manager didn't want then you shouldn't get paid for it or be entitled to an extension of time.