about variation size

char : 1byte
short int (short):2 bytes
int :4bytes
long int (long):4 bytes
bool :1byte
float :4bytes
double :8bytes
long double :8bytes

What is IDE

IDE is acronym of interface of developing environment.
there are several IDE programming that support C programming environment
like vscode ,visual studio , eclipse, intellijay, dev code, notepad ++ and so on.
But I highly recommend to install vs studio community cause it's very comfortable and easy to install.

LINK: https://visualstudio.microsoft.com/downloads/

as you can see micro soft offer this program for free.
so you don't need to worry to pay while you are studying (but if you use it for money you need to pay it's same in other programming languages too, except some languages like javascript and python. )

anyway click the download button and execute .exe or .msi extention file for proceeding .
After finishing installing run visual studio installer

you can find it in start menu if you installed it properly .
play the program and if it requires to update then update the program if not you can't proceed further more.
it can take few time.
then if it finished you can see the list visual studio series that you installed.

choose a program and update if it requires and restart if you can see like the image.

after reboot, run installer again.
and press modify button from the list.
then check C++ plug ins for using c programming language in visual studio.

and then start visual studio and choose project which available c++, make bin or console type file.

Caution : extension must be changed from .cpp to .c

Now you can finished env for developing C practice.
have fun.