1. The one year count begins the day you do it.
2. No. For married UK applicants, pretty much nothing needs to be notarized. As stated in the country specific guide:
Send originals of the immigration forms (items 1 to 5 below) and police certificates. Send photocopies of all other documents, unless instructed otherwise. Do not send your documents in transparency pockets, binders or folders. If your documents are not in English or French, send a notarized (certified) translation with a copy of the originals.
3. As above, none. Only common-law couples are required to notarize at least 2 of their family/friend letters. It's not necessary for married couples.
4. The government doesn't notarize them. A lawyer, Justice of the Peace, NOtary Public, MP, etc. can notarize documents.
5. You can apply for IEC 2015. The two apps have absolutely nothing to do with each other.
6. E-tickets and check-in confirmations are fine.
7. Mark N/A on the checklists for all forms that don't apply. If you want, you can include them but don't leave them blank; mark a big N/A across the entire page.