The number of survivors is difficult to discover, as the gunboats were loaded with troops and civilians escaping from Singapore This account claims it was “Army 97” bombers that carried out the attacks – I am not an expert on aircraft, but I presume that this means the Ki-27 ‘Nate’ http://www.kinnet...

The minimum age for Royal Navy entry was 15 yrs and 3 months, so I cannot see that he would have been 'rejected'. There was no 'transfer' between Royal and Merchant Navies

Probably MMS.311, one of the large class of Motor Minesweepers

see: https://en.wikipedia.org/wiki/MMS-class_minesweeper

MMS.311 was built at Tel Aviv, along with MMS.312. Another pair, MMS. 310 and MMS.313 were built at Beirut

From the 1947 MNL: ADMIRAL KEYES – Official Number 180948 Built Montreal, Quebec (no year) measured 133.4 feet (length) x 26 feet (beam) 285 tons ADMIRAL VERNON – ON 180950 – built Southampton 1943 measured 127.9 feet (length) x 26 feet (beam) 295 tons Some more details may be found in the National ...

The 1947 Mercantile Navy List shows several “Admirals” owned by William Phillips of Stratton Street, London W1. Admiral Fisher Admiral Grenville Admiral Hawkins Admiral Keyes Admiral Sturdie ( sic ) Admiral Vernon Sturdee is shown as being built in 1944 at Meteghan, Canada – so presumably one of MMS...

Pintail was part of the escort to coastal convoy FN.77. At 11.50 one of the ships in the convoy, the Royal Scot, detonated a mine. Pintail altered course to go to her assistance but as she approached the scene was blown up when she also triggered a mine

The group was initially attacked at 12.35 by several JU.88 aircraft but which failed to score any hits.

Second attack at approx. 16.00hrs by numerous aircraft. This resulted in the sinking of the Helka and Grimbsy.

Southern Maid picked up survivors from both ships and reached Mersa Matruh

Stoke had arrived at Tobruk having escorted some ships from Alexandria. She was attacked from 16.00 by Ju.87s and was hit by two bombs, one hit amidships and a second went through the upper deck to explode in the flat below. Several other bombs burst around her. Nine men were killed. I do not have a...

At 07.00, when Jersey as fourth in line after Kelly, Jackal and Kelvin; the Kashmir and Kipling and cruiser Gloucester were unable to enter harbour and were ordered to Gibraltar

The wreck of RN submarine Urge has been located off Malta https://www.royalnavy.mod.uk/news-and-latest-activity/news/2019/october/31/191031-ww2-submarine-urge-found-off-malta She evidently struck a mine soon after sailing from Malta and puts an end to the speculation that she was lost off the coast ...

In the Casualty Lists on Naval History net, the men you mentioned are shown, but not as being connected to Operation Jubilee: Reid is shown as being a casualty of an accident

see:

http://www.naval-history.net/xDKCas1942-08AUG.htm

I would just add one thing - apparently there were deaths - Naval History site lists twenty men missing or killed in the loss of Bittern

http://www.naval-history.net/xDKCas1940-04APR.htm

According to Dittmar & College ( British Warships 1914 – 1919 ) Auxiliary Patrol vessels were armed “ …as the supply of small weapons permitted”, so there was no standard fit. The most common weapon initially available was the 3-pdr, but they say - “The 3 pounder guns were removed from trawlers ...