I’m having twins at the end of October and am wondering do I get them a mesh bassinet each (so they can see through to each other and I can see them too, and keep them cool in the warm weather) or do we just get them a cot each (that will eventually convert into toddler bed) and have two cots beside the bed in our room for the first year? Is it safe for newborns to be in a cot or are they safer in a bassinet for the first 3-5 months? We lost our overdue daughter last year due to complications and errors made by hospital caregivers during my labour, so I’m wanting to be as careful as possible to keep my twins safe when they arrive.

I am sorry to hear of the loss of your daughter last year.

Red Nose recommends that the safest place for baby is in a cot that meets Mandatory Australian Standards
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/household-cots
There are no Mandatory Australian Standards for bassinets, however Red Nose & Product Safety does have some guidelines/buying tips when buying a bassinet.
https://rednose.org.au/article/bassinettes
https://rednose.org.au/article/baby-safe-sleeping-products
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/bassinettes

In summary, you can use bassinets or cots, from birth.
If you decide to use bassinets, check the following:

Check that any bassinets meet the guidelines as suggested by Red Nose & Product Safety:
Remove all ribbons and ties to prevent strangulation.
The sides should be at least 300 mm high, measured from the top of the mattress base, and preferably made of air-permeable material such as mesh.
Use a firm, clean, well-fitting mattress that is flat (not tilted or elevated) and is not thicker than 75mm.
If the legs fold, ensure they can be locked and won’t collapse when used.
It is recommended that a bassinet type product should be used for a short period only.
Once baby becomes active and starts to roll, the baby should be moved into a safe cot.

Another thing to consider, is co-bedding twins (in a cot), however this is also short term only.
Although surveys demonstrate that co-bedding twins at home is common (> 50%), current evidence shows that the safest way to sleep twins at home is to place them in their own cot and follow the Red Nose safe sleeping guidelines

Red Nose has the following information:

If twins must share the same sleep space, a cot is the most suitable, do not use bedding (such as sheets and blankets) and place them at opposite ends of the cot.
An infant sleeping bag used for each baby may be useful in this situation.
When the babies have reached the age where they can move freely around the cot, they must be placed in separate cots.
Babies should not co-bed with any other children.
https://rednose.org.au/article/co-bedding-twins