not true. watch the leaked Chainalysis video (e.g. currently available at https://odysee.com/@nyxmr:d/chainalysis:f, may not be in the future). they did a lot of their correlations by running nodes and observing transactions that were directly submitted through those nodes.
run your own full node.
Tuta accepts Monero as payment.
do they directly take actual XMR, or do you mean that they sell vouchers to Proxy Store that Proxy Store then resells for XMR? as far as I know, it’s the latter, and there is a huge difference between the two.
it is now. the Matrix came back online at 18:00 UTC.