Historical Data + Current Data

I have generated 3 tables using a blank query that makes an API call and fetches the data this way

Table #1 API call to get data from July 2022 - Aug 2022

Table #2 API call to get data from Sept 2022 - Dec 2022

Table #3 API call to get data from Jan 2023 - April 2023

Table #4 API call to et data from May 2023 - Aug 2023

Table #5 API call to get data from Sept 1 2023 until now

Then i took the table #1 and appended #2, #3 and #4. I also disabled load and refresh on tables #2,#3 and #4 and now I really have 

Table #1 data from July 2022 to August 2023

Table #5 data from Sept 1 2023 until now

Calendar table

I have a following questions

1. Can I delete not appended tables (2,3,4) now snce they are not needed? Currently I have load and refresh disabled on them
2. Every time i want to transform some data in the table #1 and I click on it seems to be running the query all over again. The other day I realized that my datetime was in text and I wanted to change the type to a datetime and as soon as I clicked on the table it runs the query (see dots at the top moving) and it takes forever to complete. Is there a way to disable this since it is hisrotical data and I dont need any new data for this particular table since it is data from sept 2022 to August 2023
3. Since i am new to Power BI and this is the best way I knew how to do this is there a better way to do this and speed things up?

any help/ideas/suggestions would be miuch appreciated.