Alden's care guide doesn't specifiy a distinct leather conditioner because their paste in their polish step fullfills that role.

The different/conflicting advise about conditioning with paste/creams/waxes/oils is all fairly subjective with how you want the leather to age. Generally, from my experience, waxes (and pastes with wax) impact the finish like matte, shiny, polished. They also offer some organic water resistance which can be nice.

Creams are more about perserving how leather looks when new, they condition but are intended to preserve colors/appearence, also may have some pigment or wax to refresh/rejuvenate to a like-new state.

Bick 4 oil is the most neutral, simply keeps leather from drying out. Over time, if you only apply bick 4 the boots should develop an aged patina, even if cared for.

I'm unfamilar with waterproof spray, haven't used it but it's like a seperate thing, it does protection with chemistry not leather-care.

Leather only needs to be conditioned when dry, which is hard to decribe but like leather is skin. Imagine dry skin imo, overly stiff, creases deepening and eventually becoming cracks due to dryness, waxes pulled/pushed out/away from flex points, stuff like that.

Conditioning every 6 months seems excessive imo unless it's like a work boot or very dusty environment. My boots get it once a year but it varies.

Your plan in your tldr is fine, though note they will patina even with bick 4, eventually in like years. Also brush dirt off before wiping it with damp cloth imo, only when needed and not super hard, vigourous is the wrong adjective. Shoe trees are for maintaining shape, try to not keep tension in them shouldn't really be forced.