Question on decreases

I am doing this sweater

I am to the point where I am shaping the armholes:

Dec 1 st each side every RS row…

does it matter what kind of decrease? The pattern does not specify. I usually do top down sweaters, so I am not sure of what to do.

and another question…same pattern

pattern says:

Shape Neck and Shoulders
(RS) K25 sts and turn, leaving remaining sts on a holder. Work each shoulder separately.
(WS) Bind off 4 sts, purl to end
(RS) Bind off 7 sts at beg on next 3 RS rows.
With RS facing, rejoin yarn and bind off center 28 sts, knit to end. Work left shoulder same as right shoulder, reversing shaping.

What shaping? And when did I detach my yarn? I am really confused.

Thank you for any help.

Ginny

Decs at the beg and end of the row look better if they’re ‘paired’. Generally you do ssk/skp at the beg and k2tog at the end so they slant away from the edges. But most commercial sweaters and ‘full fashion’ patterns reverse that so they slant [I]toward[/I]the edges. Your choice.

The shaping is the BOs. Knit part of the sts and turn to do the WS row, this is the first shoulder and when you finish that, cut your yarn and use another strand for the other shoulder. On the first WS row, BO 4 sts and work across. Then BO at the beg of the next 3 RS rows and that uses up all your sts.

To ‘reverse’ the shaping on the other shoulder, you swap the BOs. First BO the center sts, these are your neck. Finish the row. Turn and BO 7 sts at the beg of the WS row, finish it, turn and BO 4 sts at the beg of the RS row (this shapes the neck like on the other side). Finish the RS row and BO sts at teh beg of the next 2 WS rows.