A AT&T stock split is no different than any other stock split. AT&T is simply packaging the number of outstanding shares in a different way. For example, in a 2-for-1 split, the amount of shares will double (and the price will be divided by 2, accordingly). Say you have 100 shares of AT&T, then the day of the split you will receive 2 shares for every 1 share you hold in your brokerage account, meaning you will receive 200 shares on the stock split date. However, the price of the stock will reflect this change and your holding of AT&T (in terms of value) will remain practically the same.
A stock split does not change the fundamental value of a company. Meaning a AT&T stock split will not make the business more valuable. However, there is a psychological benefit in that the share price will be lower after the split, making shares seem more accessible to everyone and thus temporarily increasing demand and ramping up share prices. To further explore stock splits, please refer to Investopedia.
While this is not financial advice and we have not run any thorough studies on the matter, general consensus is that price tends to go up after the announcement of a stock split and before the stock split itself happens.
Unfortunately, we do not know. There might be rumors of a AT&T stock split, but the truth is that until the board proposes a shares split to its shareholders, it's all just noise.
A stock split affects options the same way it affect shares. In the case of a 2-for-1, the strike price of all the options chain post-split will be divided by 2 automatically. So if you're holding CALLs or PUTs, the strike price of the $T option will be automatically changed on the day of the split. Also, the number of shares will double. So if you have a CALL in a 2-for-1, after split you will have 2 calls to control 200 shares, and the strike price of those two CALLs would be halved.
Not all shares splits are even. Some splits, like a 3-for-2 can result in shareholders owning fractional shares. In these cases it's best to contact your broker, to be clear on how they will handle the $T shares split.