Hello and welcome. Starting with the HashkillerGUI is a good idea, but you have to make a few changes. One is unchecking "CPU only", the other is to point the Hashcat Path to the right directory where your hashcat resides. With Brute-force you also should set the Password Length.
1. I'm not quite sure what you mean by "encrypted style". If you mean the type of hashing being used, it's necassary to know that before. You encrypted with MD5, so hash type is MD5.
2. Mask: ?d?d?d?d?d
2a. Mask: "123abc" -> ?d?d?d?l?l?l
2b. Mask: "abcdef" -> ?l?l?l?l?l?l
2c. Mask: "$$abc" -> ?s?s?l?l?l (if "$" is supposed to mean special characters)
3. Yes, and you should only use hashes of the same hash type in one file. Other hashe types than the one you try cracking end up in error messages.
4. Yes. Otherwise your GPU will not be used.
There are some tutorials in german on Youtube.
Happy trying
1. I'm not quite sure what you mean by "encrypted style". If you mean the type of hashing being used, it's necassary to know that before. You encrypted with MD5, so hash type is MD5.
2. Mask: ?d?d?d?d?d
2a. Mask: "123abc" -> ?d?d?d?l?l?l
2b. Mask: "abcdef" -> ?l?l?l?l?l?l
2c. Mask: "$$abc" -> ?s?s?l?l?l (if "$" is supposed to mean special characters)
3. Yes, and you should only use hashes of the same hash type in one file. Other hashe types than the one you try cracking end up in error messages.
4. Yes. Otherwise your GPU will not be used.
There are some tutorials in german on Youtube.
Happy trying