At 70kg you could ride anywhere from 90L-110L depending on how good your balance is and how easy you want it. You could easliy get something like this
www.oneoceansportsaustralia.com/shop/wind-wing-boards in the 5'4 if you want easy and 5ft if you want a challenge.
On the wing side yes 5m will be perfect and will suit 90% of the winds when learning. If you are on a budget or just dont want to spend a fortune for you first wing these are CHEAP!! and a really good wing
www.oneoceansportsaustralia.com/wind-wings-shop You can really have the board and wing for $2250 all brand new!!
On the foil side maybe something like an Axis as they are a great well made foil with plenty of wing options as you grow and get better, I don't ride Axis so can't really say what might be the best wing to learn on but plenty of good used Axis setups around on the market that would I would say will suit.