List Update using Power Automate

I'm looking for an expert in Power Automate who can help me with automating data update within SharePoint / Microsoft list

I need a simple Power Automate flow designed to update a SharePoint list. This flow should specifically handle updating existing items..

Details: 2 lists.

List A: Title and Stock
List B: Title (lookup from A), Type (choice with values Add/Remove), Quantity

First step will be user adds list of items in list A with stocks (no flow so far)

Logic: when a user adds a record in list B, flow will check if type is Add, modify the Stock value for the respective title

Example, Item 1 has 1000 stock in list A, add a new item in list B, type Add, Quantity is 100, in this case modify the stock to be 1100

Now, add a new item in list B, type as Remove, Quantity is 300, in this case, the stock is updated to 800

Similarly, whenever a record is added in list B, check in list A, match the title and update its quantity, if Add then amend the value, if Remove, then subtract the value of stock..

Any queries feel free to discuss,

Ideal skills for this project include:
- Extensive experience with Power Automate
- Proficiency in managing SharePoint lists
- Strong understanding of flow creation and automation techniques

NOTE: please apply only if you have an expertise and demonstrates similar workflow

Question for you:

Q1. The solution will work both for Microsoft List / SharePoint List
Q2. Is it possible to have this functionality for lookup column like above, or we need to manually add name of title, open for recommendations