Advice on Feats - Changeling Rogue(Thief) + Artificer(Cartographer)

Any advice for good Backgrounds / Origin Feats / General Feats for this build? 

Planning to start Rogue to get weapon proficiencies/skills, do Artificer 3 (to get Cartographer map + teleports), then back to Thief till 17 (probably).

Drawn to Thief for Fast Hands (using scrolls / wands as BAs seems awesome in an Artificer party I am working on).

Considering using Fog Cloud / Eversmoking Bottle w/ BA Hide so will prob take Skulker at 4th/8th level to get Blindsight but definitely looking for ideas.

But what is the actual goal or playstyle you're trying to accomplish, or build problem you can't figure out?

If you plan on using an Eversmoking Bottle a good pickup would be the Skulker feat for the 10' blindsight. It would give you an easy way to get advantage since your target would be blinded by the smoke but you wouldn't.

Actually I am struggling a bit with figuring out reliable ways to trigger opportunity attacks without using my BA to read True Strike scrolls (ideally want Attack w/ Sneak Attack + BA Magic Item - Wand of Magic Missile/Fireballs + reaction/opportunity attack + Sneak Attack.

Only Finesse weapon I found that works with Polearm Master is the Wardancer Spear (3rd party) and it seems a bit OP (double attack w/ 1 hand).

Considering carrying Shortsword (5' Reach) and Whip (10' reach) in Darkness or Cloud/Smoke to have greater likelihood of getting OAs from enemies blindly moving around.

Does not seem to be a way to get OAs with ranged weapons - although seems like if an enemy provokes an OA at 10' range (Whip) I can cast True Strike (War Caster) and attack with a Crossbow.

Fast Hands is for items like Eversmoking Bottle: "As a Magic action, you can open or close this bottle.". In contrast, the general rules for Spell Scrolls: "If the spell is on your spell list, you can read the scroll and cast its spell without Material components.". Fast Hands permits the first but not the second. It does not let you cast spells as a Bonus Action, regardless of whether that ability comes from a magic item or not.

Also, you'll probably discover that unless you're doing a one-shot (where you can design a character for one specific level), it's almost always better to focus on a single class than try to cherry-pick multiple low level abilities - those low level abilities you're taking aren't as good as the higher level ones you're delaying/missing in most cases. While most classes eventually 'cap out' at some point, this point is generally beyond the level range of most campaigns.