How do things like charges or uses per day affect the requirements of crafting magic items, & are there any source rules governing this

There are two official optional rulesets for crafting

Both are optional and require that you work with your DM as to if they're an option and how they'd work. In either place that these rules appear, they are optional variants to the base rules.

Dungeon Master's Guide

The first official optional rules released appear in the Dungeon Master's Guide in chapter 6 as part of the "Downtime Activities" section:

Crafting a Magic Item

Magic items are the DM’s purview, so you decide how they fall into the party’s possession. As an option, you can allow player characters to craft magic items.

Within these rules, there are the following requirements:

• a formula that describes the construction of the item
• the character must also be a spellcaster with spell slots and must be able to cast any spells that the item can produce (and expends the relevant spell cost each day during crafting)
• the character must meet a level minimum determined by the item’s rarity
• a required gold and time cost to craft the item during downtime (consumable cost half as much as other magic items)

\begin{array}{c|c|c} \text{Rarity}&\text{Cost}&\text{Minimum Level}\\ \hline \text{Common}&\text{100 gp}&\text{3}\\ \text{Uncommon}&\text{500 gp}&\text{3}\\ \text{Rare}&\text{5,000 gp}&\text{6}\\ \text{Very Rare}&\text{50,000 gp}&\text{11}\\ \text{Legendary}&\text{500,000 gp}&\text{17}\\ \end{array}

Xanathar's Guide to Everything

An alternative ruleset is part of the optional variant to downtime as a whole (and one I personally think is more fleshed out) that appears in the supplement Xanathar's Guide to Everything in the "Downtime Revisited" section of chapter 2:

Crafting Magic Items. Creating a magic item requires more than just time, effort, and materials. It is a long-term process that involves one or more adventures to track down rare materials and the lore needed to create the item.

Within these rules, there are the following requirements:

• a formula for a magic item in order to create it
• an exotic material to complete it. This material can range from the skin of a yeti to a vial of water taken from a whirlpool on the Elemental Plane of Water. Finding that material should take place as part of an adventure. (the suggested challenge rating of the creature to face, though not necessarily harvest the material from, appears in the table below)
• whatever tool proficiency is appropriate, as for crafting a nonmagical object, or proficiency in the Arcana skill.
• a required gold and time cost to craft the item during downtime (consumable cost half as much as other magic items). Do note that downtime rules as a whole are revised when using the Xanathar's Guide to Everything rules

\begin{array}{c|c|c|c} \text{Rarity}&\text{Challenge Rating}&\text{Time}&\text{Cost}\\ \hline \text{Common}&\text{1-3}&\text{1 workweek}&\text{50 gp}\\ \text{Uncommon}&\text{4-8}&\text{2 workweeks}&\text{200 gp}\\ \text{Rare}&\text{9-12}&\text{10 workweeks}&\text{2,000 gp}\\ \text{Very Rare}&\text{13-18}&\text{25 workweeks}&\text{20,000 gp}\\ \text{Legendary}&\text{19+}&\text{50 workweeks}&\text{100,000 gp}\\ \end{array}

2000gp/day

The feat only gives a very short description of the item creation rules, and then refers the reader to the actual rules:

Benefit: You can create a wide variety of magic wondrous items. Crafting a wondrous item takes 1 day for each 1,000 gp in its price. To create a wondrous item, you must use up raw materials costing half of its base price. See the magic item creation rules in Magic Items for more information.

The magic item creation rules are authorative and supersede the feat description. The "1 day per 1000 gp" rule is merely a convenient combination of the "8 hours per day", and "1 hour per 1000 gp" rules for the sake of brevity. Since the magic item creation rules state that accelerated crafting reduces the time spent to 4 hours per 1000 gp, but does not touch on the 8 hour daily limit, there is no reason to assume that the daily crafting time limit is suddenly reduced to 4 hours.