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No exchange in the US allows trading something at $26.107 that is in fact explicitly against the rules.

HFTs do not see your buy order before it reaches the market and then buy them ahead of you to sell them back to you.

Your understanding of the stock markets and HFT is inaccurate and you are spreading incorrect information.

Retail orders are generally routed to markets using a SOR and do not overage 100% of the full order. There are latency differences between exchanges / ATS'. If you are very fast is possible to post passively on multiple venues and exploit those latency differences to assume if you see a small ping on market x there is more behind it. You can gain book position and the spread with this information, if you are fast.

Sure, but hiding large order flow wasn't invented with the rise of HFT.

It has always been the case that a market maker could look at orders coming in and bet that it was the tip of a large order flow and thereby adjust the prices he was offering. It's just that gut instinct, good ole boy networks, and luck have been replaced with network infrastructure, systematic engineering and analytics.

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