No. Rounding can be one way of formatting, but generally they are very different. Rounding just changes the amounts of decimal places displayed. Formatting can do that and a huge amount of other things, such as the type of number, like currency or percentage. Formatting can change the size, the font and the colour. Formatting can change underling, italics and bolding. So it can change a lot of things. Rounding is just one specific thing you can do.
Merge brings one to several individual cells from Excel into Word. The formatting in the merged Word document depends on Word, not Excel. If you would like to retain the same formatting as you had in Excel, then format the target location in Word to match the cell from Excel.
Use format painter
No. Only the formatting will change. The actual values will stay the same, even if a value appears to have rounded up, like if you reduced the amount of decimal places.
An estimate is an educated guess based on prior knowledge. Rounding off is knowing the exact value but rounding it to the nearest whole number.
They are the same thing, excel is Microsoft's spreadsheet programme.
Any conflicting formatting will be replaced by the style that is being applied. Whatever formatting that may have already been applied to the cell that is different to the style will be set to be the same as the style.
It will stay formatted until the formatting is changed to something else, so it can in effect have the same format permanently if it is not changed.
it's the Same thing
No, it is not. Estimating may be rounding but need not be.
Yes. 12300 rounded to the nearest hundreds is 12300. No problem!
The same formatting as the cells above of them
They are not.