I would really appreciate a sense check and some guidance on my navigation technology for my forthcoming Cape to Cairo (by motorbike).

I already have:
Whatever the latest iPhone is (6s?)
An old Garmin eTrex Legend HCx i'v hardly ever used
Two Michelin paper maps as recommended by Chris Scott for Africa
An new ASUS transformer T100HA

I have mapped my route in Google maps and noted down GPS points along the route.

I am intending (subject to comments below) to get an up to date Africa map for my eTrex which I will bar mount and use for directional navigation to my GPS points (assume this will not be route guidance, just "head north east" style).

All the advice seems to be to get the Tracks4Africa maps. I suspect i cannot run this on the eTrex (as it is too old - T4A state their maps cant be used with certain eTrex units). Is there an iPhone app that I can use without having to buy SIM cards etc on route? If so that might be my best option?

There seems to be some talk of Mapsource on the T4A. I recall that this relates to being able to create custom maps to follow and upload to the eTrex or equivalent. I never really got my head around that, hence the limited use i have made of the eTrex. Anything i do I will need to do with the ASUS since that's all i am taking computerwise.

I was also thinking of getting a satellite phone since i am travelling solo. However comments on the HUBB have made me consider the Delorme Inreach Explorer instead. If I go for this I assume i can then dispense with the eTrex altogether and use this as the basic GPS Navigator?

If someone can gently explain the best way to get myself around Africa using this technology i'd be VERY grateful. If you are tech savvy please do it in an way that feels like you are patronising me and that will be perfect :-)

Cheers
Andy