They are the same.
This is not correct.
The size of your trade is the size of your position.
The “distance” (in pips) [I]from your [U]entry[/U] to your stop-loss[/I] is your [B]risk in pips[/B]. This risk (in pips) times the relevant pip-value is your [B]risk in dollars[/B] (or whatever your account currency happens to be).
The “distance” [I]from the [U]current price[/U] to your stop-loss[/I] (measured either in pips or dollars) is [B]not[/B] a metric commonly used in forex trading.
Correct.
Position size can be stated as the [I]notional amount[/I] of your trade — for example, 1 standard lot (100,000 units) of GBP/USD; or as the [I]notional value[/I] of your trade — for example, $141,200, which would be the notional value of 1 standard lot of GBP/USD (at a GBP/USD price of 1.4120).
.