No (not every word like this is feminine) and No (the word Allah is neither feminine nor masculine).
The letter "ت" or "ة" is an indication for female names, but not exclusively
Not all words that end with the letter "ت" or "ة" refer to a feminine word in Arabic, not even if this word is a "noun" for example:
If we call a person genius we say Nabighah to ...
Sabab is used as synonym for 'illah, and the two are often used
interchangeably. Yet the ulema of usul tend to use sabab in reference to devotional matters (ibadat) but use 'illah in all other contexts. Thus it is said that the arrival of Ramadan is the cause (sabab) of fasting but that intoxication is the 'illah of the prohibition in wine-drinking.