If I'm not wrong, only the DNA-based vaccines (e.g., AstraZeneca and Janssen) are officially recognized as being able to cause blood clots.
For example, this article (link below) found that:
"In conclusion, analysis of the EMA pharmacovigilance database shows that CVST [a type of blood clot disorder] occurring after the ChAdOx1 nCov-19 vaccine [AstraZeneca] has a clinical profile that is different from patients with CVST unrelated to vaccination....CVST cases occurring after mRNA vaccines were similar to pre-COVID-19 CVST cases, pointing towards background incidence rather than association with the vaccine."
Link: https://pubmed.ncbi.nlm.nih.gov/34293217/
This means that the blood clot incident rate from the mRNA vaccine is the same as pre-covid times, suggesting a coincidental association rather than causation.
To establish causation, a few factors are needed: timing, mechanism of action, and incidence rate. Thus, we know that Covid-19 can cause blood clots because about 1 in 5 patients in ICU due to Covid-19 suffer severe blood clots (timing: soon after covid-19; incidence rate: much higher than normal). And Covid-19 is known to dysregulate blood vessel functions via various mechanisms, such as excessive inflammation, ACE2 dysregulation, etc.
For the second question, I came across this preprint that found that:
"Both smoking and use of nicotine and flavor-containing e-cig led to upregulations of pro-inflammatory cytokine production and expression of genes related to inflammasomes."
Link: https://www.biorxiv.org/content/10.1101/2020.07.13.198630v1
So, it seems that as long as the product contains nicotine, it can increase the expression of ACE2 receptor.
But there are some studies that found that smoking or COPD (chronic obstructive pulmonary disease; almost always caused by smoking) decreased ACE2 receptor expression instead. So, I think the effects of smoking/nicotine/COPD on ACE2 are still inconclusive. You read more about this here: https://www.sciencedirect.com/science/article/pii/S030698772100147X
