Thanks for considering Aspose.
Aspose for Cloud can be used with any platform which supports REST calls including .NET. Following are replies to your questions.
a) Max file size can be up to 100MB depending upon your package. Please check pricing packages for more details.
b) Word, Excel, PowerPoint, PDF, OpenOffice, HTML, Images and many other formats are supported. Please visit Cloud APIs page and click Learn More button against any API to check file formats supported by that API.
c) If you want to know about mail merge templates, you can use any MS Word or HTML format as template with Aspose.Words for Cloud and use MS Excel files as smart marker templates. If you want to convert to other formats, you can use any file format supported by Aspose APIs as described in point b.
d) Please check pricing packages for more details.
e) Aspose for Cloud is platform independent and can be used with any language/platform which supports REST.
f) Aspose for Cloud APIs access request data in JSON/XML format and return response as JSON/XML format.
g) Not supported but is in our near future plans.
h) Not supported but is in our near future plans.
j) Technical support is free and our normal turnaround time is within 24 hours but we try to reply your queries as early as possible. As far as bugs or new feature requests are concerned, such issues are fixed by our product team. We try to fix the issues as soon as possible but some complex issues can be delayed depending upon their complexity.
Please feel free to contact us in case you have further comments or questions.