Need Help Calculating State Estimated Tax Payments

Hello,

I am creating a spreadsheet to calculate and model my estimated taxes for the year. This is to make sure I dont make any mistakes with estimated taxes, and to save me time in future years.

(If you're wondering, I am a happy TurboTax customer but prefer to estimate my taxes this way)

Sources of Income:

I am semi-retired and worked part time throughout the year from my home in Charlotte, NC for 2 jobs, both remote. My sources of income throughout the year were:

A. $25K from a remote part-time W2 job for a company located in NY (this company's pay statements / W2 have tax deductions for the state of NY).

B. $45K from a remote part-time W2 job for a company located in CA (this company's pay statements / W2 have tax deductions for my LOCAL state of NC, so I take it that this income is "attributed" to the state of NC, not CA)

C. $50K from my remote rental property in the state of CA.

D. Short Term (ST) Capital Gains income: $90K from Short term capital gains.

E. Long Term (LT) Investing income: $250K from Long term capital gains. 

All trading / investing was done from my home in Charlotte, NC and may not be repeatable.

I am trying to calculate my estimated tax payments for: Federal, State of NC, State of CA, State of NY

I have some Questions:

Q1. For estimating federal taxes, income (and ST capital gains) are taxed at income tax rates (based on tax tables), long-term capital gains are currently taxed at 15% or 20%. Is this correct?

SEE https://www.nerdwallet.com/article/taxes/federal-income-tax-brackets

Federal income tax (F1) would be calculated using: A+B+C+D

Federal LT capital gains (F2) would be calculating using: E

And then total Federal tax owed would be F1+F2, minus any standard federal deductions. Is this correct?

Q2. For estimating state taxes:

The state of NC has a flat 5.25% tax rate. SEE https://www.tax-brackets.org/northcarolinataxtable

Would the total NC State tax owed be calculated based on: B only (taxed at 5.25%), B+D+E (taxed at 5.25%), or A+B+C+D+E (taxed at 5.25%)?

The state of CA has a tiered tax structure. SEE https://www.tax-brackets.org/californiataxtable or https://www.nerdwallet.com/article/taxes/california-state-tax

Would the total CA State tax owed be calculated based on: C only (taxed based on the CA tax tables), or A+B+C+D+E (taxed based on the CA tax tables)?

The state of NY also has a tiered tax structure. SEE https://www.nerdwallet.com/article/taxes/new-york-state-tax

Would the total NY State tax owed be calculated based on: A only (taxed based on the NY tax tables), or A+B+C+D+E (taxed based on the NY tax tables)?

Q3. It seems crazy that I would have to pay taxes on ST and LT capital gains taxes for EACH state I had income in. Surely it would only be taxed at the federal (and perhaps only my primary state of residence), correct? How to prevent double-taxation (and penalties), if living in one state and working remotely in others?

Q4. When estimating state taxes, similar to the federal standard deduction, states also have a standard deduction. Can the State Standard deduction be applied for *every* state I earned income from, or only to my primary state of residence (NC)?

Q5. When calculating estimated tax payments for Q1-Q4 for the state of NC, where can I find the Percentage of Tax due for each quarter to avoid the penalty? What is the penalty % rate? A link to an official resource would be appreciated (I couldn't find one, despite quite a bit of time googling)

Q6. The maximum net capital loss in any tax year is $3,000. Is this applied on ST (short-term) capital gains only, or ST+LT?

Q7. When does NEI / Net Investment income of 3.8% come into effect? Would it apply to me?

Thanks for responding.