TRON congestion affects how long a transaction takes to confirm, but it's historically had little bearing on TRX's price itself.
A card payment has no price history to check — the fiat price is fixed; TRX's Stars-equivalent price moves with the market instead.
Anyone who already tracks TRX's price closely won't find anything new here — this page is aimed at buyers checking for the first time.
It covers recent trading history, giving a general sense of how TRX has moved rather than a full historical archive.
Yes — TRX's price is the same regardless of which network it's sent on; only the transaction fee changes with TRON.