Hello letz,
You need to perform DB upgrade as it is mandatory Pre-requisite if you are planning to upgrade ECC 6 EHP7 NW SP08 or higher as per SAP Note 1951491.
I would suggest to follow approach First approach. Upgrade DB and then go for EHP 7 Upgrade.
PS: if you are selecting EHP7 SP8 as target stack in MOPZ then the calculated stack will be EHP7 SP8 NW10.
Means NW Stack (Netweaver components like BASIS,ABAP etc level) will be +2 than the selected Target SP Stack level.
Regards,
Sahil