[*] I think ravenous hydra will still take precedence over bloodthirster because the AOE heal on minions and the wave clear are very strong. You can follow it up with bloodthirster to take advantage of the 30% lifesteal early on then BotRK for a total of 40% life steal
[*] synergies with every single item in the build - the life steal, the heal from death's dance and the shield from eclipse. Also, it technically should syngergise with second wind, triumph, legend bloodline, and fleet footwork -- to be tested

[*] Weirdly, you can rush warmog first with shyvana because her ult allows you to meet the health requirements for the passive. which means that after a fight, whenever you are low, you can retreat while in dragon form or with dragon form to go back into E spam mode. Since you won't be hit while hitting E from the back, you'll technically be able to proc the passive and restore all your health back and go back in the fight again without needing to recall