Regular members of the senior team this year, all are in talks with the Saints to extend their contracts beyond this season.
Re-signing the promising group would be significant for St Kilda, which is now well and truly rebuilding under coach Scott Watters and promoting its young talent.
Head of football Chris Pelchen told AFL.com.au talks were progressing well with all three and the club was confident of retaining the key youngsters.
It is understood Webster has already signed with the Saints, with the new deal yet to be announced. Newnes is committed to reaching an agreement with the club.
That represents the end of a wasteful draft period between 2006 and 2010 that set the club back on-field.
Watters recently said the Saints had the AFL's "worst retention rate from a recruitment point of view if you look at what we've recruited in that time and what remains at the club".
Of the 24 players drafted between 2006 and 2010 at the NAB AFL Draft, only six remain on the list (Jamie Cripps and Tom Lynch are with other AFL clubs after being traded).
When trade periods and rookie drafts are included, just 12 players recruited during that period are still on the list.
Ross has shown promise as an inside midfielder this season, averaging 15 possessions in eight games, including a personal best 22 against the Western Bulldogs in round nine.
The 20-year-old was recruited with pick No.25 in the 2011 Draft, playing one game in his debut season.
Webster has played the last five games after making his debut in round seven, fitting into the team as a tough half-back with a damaging left foot kick.
Recruited with pick No.42 in 2011, the 19-year-old has impressed after shin splints restricted him to three VFL games in his first season.
Newnes, 20, has missed just two games this season after suffering concussion against Greater Western Sydney in round three.
Recruited with pick No.37 in 2011, he also played seven games in his debut season, slotting in across half-back.
Watters has been encouraged by the trio's contributions this year and all are expected to play more midfield minutes as the season progresses.
"They can play, they just need time," the coach said following the Saints' loss to West Coast in round 11.
"I'm excited to see where they're going to be after three, four, five pre-seasons."
Nathan Schmook is a reporter for AFL Media. Follow him on Twitter: @AFL_Nathan
