Clarifications: TWF, Craft, and Pact Weapon

[GutterFace]

So i have read through the books (Phb and Dm) but i do not claim to have them memorized now nor know every notation.
so i need some clarifications if possible if anyone can help.

just asking for pure RAW if possible.

Can you make a Pact Weapon (warlock) an improvised weapon without disadvantage (assuming you would not have to take Tavern Brawler)?

Does anyone know the page where it lists the costs to craft acid? does that cost include a glass flask for it?

lastly the great TWF 5.0 question....how on earth does this work...im confused. You have to have a bonus action to make an off hand attack? or every attack action you could make a main and off hand attack if you had the feat/class feature?

[CrusaderJoe]

lastly the great TWF 5.0 question....how on earth does this work...im confused. You have to have a bonus action to make an off hand attack? or every attack action you could make a main and off hand attack if you had the feat/class feature?

TWF is a basic rule not a class feature. The feat just enhances it a bit.

Each turn you get a single bonus action. You may use that bonus action if you have an ability that says to use the bonus action. If you are wielding two light weapons then you may take advantage of a bonus action called TWF.

On your turn you may use said bonus action to make an attack with your offhand weapon dealing just the weapon damage and no modifiers. You may use Str or Dex for these attacks. Your normal action attack gets the modifier to it.

Action (main hand): Attack with Handaxe: 1d20 + Prof + Str or Dex
Bonus Action (off hand): Attack with Handaxe: 1d20 + prof + str or Dex

Main hand damage: 1d6 + Str or Dex
Off hand damage: 1d6.

Generally not worth it unless you have a rider ability such as Sneak Attack that works on a hit and you missed with tour main attack.