Good ideas but she needs raw physical strength for a start. Sakura has only displayed Chakra Enhanced Strength. Tsunade has shown to be able to create fissures with one finger with no sign of chakra whatsoever.
The only reason Orochimaru hasn't been able to master Sage Mode is because he hasn't (yet) had a host body strong enough.
I doubt that there is a Slug Sage Mode because the advantages that it could offer are limited. Katsuyu has only really displayed the ability to spit acid, heal and seperate herself. Slugs don't appear to offer a great deal of physical advantages like snakes or toads (speed, reflexes, strength etc), so a SGSM would seem pretty pointless.
Plus, Tsunade has shown her Sōzō Saisei and it's more advanced version, Byakugō.
Sakura just isn't mean't for the frontlines, she is one of the best medical nin in the world but put her 1 vs 1 against a reputable ninja and she is gonna have problems.