Hi
<blockquote>How can I remove the text “That’s all” or “Next project” in the portfolio layout?</blockquote>
Open this file languageen-GBen-GB.tpl_ja_sugite.ini
TPL_FILTER_PROJECT = "Filter Project"
TPL_ALL_PROJECT ="All Project"
TPL_INFINITY_NEXT ="Next project"
TPL_JSLANG_FINISHEDMSG ="That's all"
TPL_GUTTER_IN_GRID ="Gutter of items"
TPL_GUTTER_IN_GRID_DESC ="Gutter of items in layout grid"
About your second question please take a look HERE at the documentation page
Specifically at the Portfolio Layout section you can manage through your menu item settings