A4o raise on BU vs UTG limp

PokerStars - $0.02 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

Hero (BTN): 100 BB
SB: 172.5 BB (VPIP: 36.36, PFR: 27.27, 3Bet Preflop: 0.00, Hands: 11)
BB: 119.5 BB
UTG: 62.5 BB (VPIP: 83.33, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 6)
MP: 100 BB (VPIP: 33.33, PFR: 33.33, 3Bet Preflop: 0.00, Hands: 7)
CO: 197 BB (VPIP: -, PFR: -, 3Bet Preflop: -, Hands: 1)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 4♥ A♠

UTG calls 1 BB, fold, fold, Hero raises to 4.5 BB, SB calls 4 BB, fold, UTG calls 3.5 BB

Flop: (14.5 BB, 3 players) 5♦ 6♦ T♣
SB checks, UTG checks, Hero checks

Turn: (14.5 BB, 3 players) A♣
SB checks, UTG checks, Hero bets 10 BB, fold, UTG calls 10 BB

River: (34.5 BB, 2 players) 7♦
UTG bets 20 BB, fold

My questions here are on the preflop and on the river.

Preflop, should I raise the hand, or just fold?

The way I played, on the river I cant call, right?