The app obeys the System font settings i.e. in Settings/Display/Font Size. You can also increase the font size by swiping down from the top and selecting "Settings". In the "Preferences" tab there are options to set a larger font and, in the light theme, you can also set a heavier font. You can also pinch-to-zoom in the article view screen.
The most common reason is that people enter the URL for a web page rather than an RSS feed. The app will detect that and scan the page but sometimes those web pages, despite listing feeds, don't declare them in the standard way for readers to detect. Try to open the feed in the browser, then select "Open in FeedMinder" (or "Open in RSS Savvy") from the Browser menu.
The app does a number of things to get a good favicon, including checking both the feed metadata and the root website for a good favicon. However, if the favicon is low quality (will appear blury in the app) it is discarded. At this time, you can not select your own favicon.