All the trades would settle, but you would need extra cash or a margin account. In a cash account, there's rules about selling stocks before the purchase funds have settled.
The move to T+2 settlement last decade reduces the requirements, and T+1 later this decade would reduce them further.
Dividends and corporate actions aren't a big deal. Those all have announcement dates and record dates. If you hold the shares at the close of market on the record date, you will get the dividend or other proceeds. So if you always manage to buy at close, you will always get those benefits. The only complication would be if you want to oppose a merger and have standing to sue; or I guess if you were an injured party in any other shareholder lawsuit. Lots of tax paperwork too.
The move to T+2 settlement last decade reduces the requirements, and T+1 later this decade would reduce them further.
Dividends and corporate actions aren't a big deal. Those all have announcement dates and record dates. If you hold the shares at the close of market on the record date, you will get the dividend or other proceeds. So if you always manage to buy at close, you will always get those benefits. The only complication would be if you want to oppose a merger and have standing to sue; or I guess if you were an injured party in any other shareholder lawsuit. Lots of tax paperwork too.